Lenses, devices and methods for ocular refractive error

ABSTRACT

Certain embodiments are directed to lenses, devices and/or methods. For example, a lens for an eye having an optical axis and an aberration profile along its optical axis, the aberration profile having a focal distance and including higher order aberrations having at least one of a primary spherical aberration component C(4,0) and a secondary spherical aberration component C(6,0). The aberration profile may provide, for a model eye with no aberrations and an on-axis length equal to the focal distance: (i) a peak, first retinal image quality (RIQ) within a through focus range that remains at or above a second RIQ over the through focus range that includes said focal distance, where the first RIQ is at least 0.35, the second RIQ is at least 0.1 and the through focus range is at least 1.8 Diopters; (ii) a RIQ of 0.3 with a through focus slope that improves in a direction of eye growth; and (iii) a RIQ of 0.3 with a through focus slope that degrades in a direction of eye growth. The RIQ may be Visual Strehl Ratio or similar measured along the optical axis for at least one pupil diameter in the range 3 mm to 6 mm, over a spatial frequency range of 0 to 30 cycles/degree inclusive and at a wavelength selected from within the range 540 nm to 590 nm inclusive.

CROSS REFERENCE TO RELATED MATERIALS

This application claims priority to Australian Provisional Application No. 2012/901382, entitled, “Devices and Methods for Refractive Error Control” filed on Apr. 5, 2012, and Australian Provisional Application No. 2012/904541 entitled “Lenses, Devices and Methods for Ocular Refractive Error”, filed on Oct. 17, 2012. These applications are incorporated herein by reference in their entirety.

FIELD

The disclosed embodiments include lenses, devices and methods for changing or controlling the wavefront of light entering an eye, in particular a human eye.

Particular disclosed embodiments include lenses, devices and methods for mitigating/addressing ocular refractive error, in particular in human eyes. The ocular refractive error may for example arise from myopia or hyperopia, with or without astigmatism. The ocular refractive error may arise from presbyopia, either alone or in combination with myopia or hyperopia and with or without astigmatism.

The disclosed embodiments of lenses, devices and methods include embodiments that address foveal vision and embodiments that address both foveal and peripheral vision.

Examples of lenses in the fields of the disclosed embodiments include contact lenses, corneal onlays, corneal inlays, and lenses for intraocular devices (both anterior and posterior chamber).

Examples of devices in the fields of the disclosed embodiments include accommodating intraocular lenses and electro-active spectacle lenses.

Examples of methods in the fields of the disclosed embodiments include methods of changing the refractive state/wavefront of light entering an eye and received by a retina of the eye (e.g. refractive surgery, corneal ablation), methods of design and/or manufacture of lenses and optical devices, methods of surgery to alter the refractive state of an eye and methods of controlling stimulus for progression of eye growth.

BACKGROUND

For an image to be perceived clearly, the optics of the eye should result in an image that is focussed on the retina. Myopia, commonly known as short-sightedness, is an optical disorder of the eye wherein on-axis images are focussed in front of the fovea of the retina. Hyperopia, commonly known as long-sightedness, is an optical disorder of the eye wherein on-axis images are focussed behind the fovea of the retina. The focussing of images in front of or behind the fovea of the retina creates a lower order aberration of defocus. Another lower order aberration is astigmatism. An eye may also have higher order optical aberrations, including for example spherical aberration, coma and/or trefoil. Many people experiencing natural refractive error are progressing (the refractive error is increasing over time). Progression is particularly widespread in people with myopia. Schematic representations of eyes exhibiting myopia or hyperopia and astigmatism are shown in FIGS. 1A-C respectively. In a myopic eye 100, the parallel incoming beam of light 102 passes the refractive elements of the eye, namely, the cornea 104 and crystalline lens 106, to a focal point 108 short of the retina 110. The image on the retina 110 is therefore blurred. In a hyperopic eye 120, the parallel incoming beam of light 122 passes the refractive elements of the eye, namely, the cornea 124 and crystalline lens 126, to a focal point 128 beyond the retina 130, again rendering the image on the retina 130 blurred. In an astigmatic eye 140, the parallel incoming beam of light 142 passes the refractive elements of the eye, namely, cornea 144 and crystalline lens 146, and results in two foci, namely tangential 148 and sagital 158 foci. In the example of astigmatism shown in FIG. 1C, the tangential focus 148 is in front the retina 160 while the sagital focus 158 is behind the retina 160. The image on the retina in the astigmatic case is referred to as circle of least confusion 160.

At birth human eyes are hyperopic, i.e. the axial length of the eyeball is too short for its optical power. With age, from infancy to adulthood, the eyeball continues to grow until its refractive state stabilizes. Elongation of the eye in a growing human may be controlled by a feedback mechanism, known as the emmetropisation process, so that the position of focus relative to the retina plays a role in controlling the extent of eye growth. Deviation from this process would potentially result in refractive disorders like myopia, hyperopia and/or astigmatism. While there is ongoing research into the cause of deviation of emmetropisation from stabilising at emmetropia, one theory is that optical feedback can provide a part in controlling eye growth. For example, FIG. 2 shows cases that would, under a feedback mechanism theory of the emmetropisation process, alter the emmetropisation process. In FIG. 2A, the parallel incoming beam of light 202 passes through a negative refractive element 203 and the refractive elements of the eye (the cornea 204 and crystalline lens 206), to form an image at focus point 208, overshooting the retina 210. The resulting image blur on the retina, called hyperopic defocus, is an example of defocus that may encourage eye growth under this feedback mechanism. In contrast, as seen in FIG. 2B, the parallel incoming beam of light 252 passes through a positive refractive element 253, the refractive elements of the eye (cornea 254 and crystalline lens 256) to form an image at focus point 258 in front of the retina 260. The resulting image blur, called myopic defocus, on this retina is considered to be an example of defocus induced at the retina that would not encourage eye growth. Therefore, it has been proposed that progression of myopic refractive error can be controlled by positioning of the focus in front of the retina. For an astigmatic system, the spherical equivalent, i.e. the mid-point between the tangential and sagital foci, may be positioned in front of the retina. These proposals have not however provided a full explanation or solution, particularly in the case of progressing myopia.

A number of optical device designs and refractive surgery methods have been proposed to control the growth of the eye during emmetropisation. Many are generally based on refinements to the idea summarised above that foveal imagery provides a stimulus that controls the growth of the eye. In humans, the eye grows longer during emmetropisation and can not grow shorter. Accordingly, during emmetropisation an eye may grow longer to correct for hyperopia, but it can not grow shorter to correct for myopia. Many proposals have been made for addressing myopia progression, some of which are summarised below.

U.S. Pat. No. 6,752,499 (Aller) proposes the use of bifocal contact lenses for myopic participants who exhibit near-point esophoria, for providing a stimulus for reducing/controlling myopia progression. U.S. Pat. No. 7,025,460 (Smith et al) proposes the use of corrective eye lenses that shift the focal plane in front of the peripheral retina. U.S. Pat. No. 7,506,983 (To et al) proposes a method of treating myopia progression in human eyes by producing a secondary myopic image by use of Fresnel optics, while correcting the myopia of the candidate via the refractive portion of the lens. U.S. Pat. No. 7,997,725 (Phillips) proposes a method of simultaneous vision, wherein one part of the correcting lens corrects for pre-existing myopia while another part has less negative power than the focal power of the lens to be able to produce simultaneous myopic defocus and thereby aid in the retardation of myopia progression. U.S. Pat. No. 6,045,578 (Collins and Wildsoet) proposes the addition of positive spherical aberration at the fovea to provide a stimulus that will reduce and/or control myopia progression. U.S. Pat. No. 7,401,922 (Legerton et al) proposes a method and system of treating myopia progression in myopic patients by inducing certain aberration profiles that have positive spherical aberration to produce a wavefront disposed in front of the retina. U.S. Pat. No. 7,803,153, B2 (Thorn et al) proposes a method of preventing myopia progression through identification and correction of all optical aberrations, including higher order aberrations.

In addition to proposed optical strategies to counter the development of refractive error and its progression, in particular myopia, there has also been interest in strategies that involve non-optical intervention like pharmacological substances, such as atropine or pirenzipine.

Another condition of the eye is presbyopia, in which the eye's ability to accommodate is reduced or the eye has lost its ability to accommodate. Presbyopia may be experienced in combination with myopia, hyperopia, astigmatism and higher order aberrations. Many different methods, devices and lenses to address presbyopia have been proposed, including in the form of bifocal, multifocal or progressive addition lenses/devices, which simultaneously provide two or more foci to the eye. Three common types of lenses used for presbyopia are centre-near, centre-distance aspheric multifocals and concentric (ring-type) bifocals alternating between distance and near powers.

In addition, on occasion it is necessary to remove the crystalline lens of an eye, for example if the person is suffering from cataracts. The removed natural crystalline lens may be replaced by an intraocular lens. Accommodating intraocular lenses allow the eye to control the refractive power of the lens, for example through haptics extending from the lens to the ciliary body.

SUMMARY

Disclosed herein are various lenses, devices and methods for providing an aberration profile for an eye. Characteristics of aberration profiles and methodologies for identifying aberration profiles are described for myopic eyes, hyperopic eyes and presbyopic eyes. In addition lenses, devices and methods for an eye with astigmatism are disclosed.

In one embodiment, a lens for an eye has an optical axis and an aberration profile about its optical axis, the aberration profile having a focal distance and including at least one of a primary spherical aberration component (C(4,0)) and a secondary spherical aberration component (C(6,0)). The aberration profile provides a retinal image quality (RIQ) with a through focus slope that degrades in a direction of eye growth; and a RIQ of at least 0.30. The RIQ is Visual Strehl Ratio measured along the optical axis for at least one pupil diameter in the range 3 mm to 6 mm, over a spatial frequency range of 0 to 30 cycles/degree inclusive and at a wavelength selected from within the range 540 nm to 590 nm inclusive. In other embodiments the RIQ measure may be different.

In another embodiment, a lens includes an optical axis and an aberration profile about the optical axis that provides a focal distance for a C(2,0) Zernike coefficient term; a peak Visual Strehl Ratio (‘first Visual Strehl Ratio’) within a through focus range, and a Visual Strehl Ratio that remains at or above a second Visual Strehl Ratio over the through focus range that includes said focal distance, wherein the Visual Strehl Ratio is measured for at least one pupil diameter in the range 3 mm to 5 mm, over a spatial frequency range of 0 to 30 cycles/degree inclusive, at a wavelength selected from within the range 540 nm to 590 nm inclusive, and wherein the first Visual Strehl Ratio is at least 0.35, the second Visual Strehl Ratio is at least 0.10 and the through focus range is at least 1.8 Diopters.

In one embodiment, a method for a presbyopic eye includes identifying a wavefront aberration profile for the eye, the wavefront aberration profile including at least one spherical aberration term. The prescription focal distance of the aberration profile is determined taking into account said spherical aberration and wherein the prescription focal distance is at least +0.25 D relative to a focal distance for a C(2,0) Zernike coefficient term of the wavefront aberration profile. The method includes producing a device, lens or corneal profile for the eye to affect said wavefront aberration profile.

In one embodiment, a method for a myopic eye includes identifying a wavefront aberration profile for the eye and applying or prescribing the aberration profile. The wavefront aberration profile includes at least one spherical aberration term, wherein the prescription focal distance of the aberration profile is determined taking into account said spherical aberration and wherein the prescription focal distance is at least +0.10 D relative to a focal distance for a C(2,0) Zernike coefficient term of the wavefront aberration profile. The wavefront aberration profile also provides a degrading retinal image quality in the direction posterior to the retina.

A method for a hyperopic eye, the method comprising identifying a wavefront aberration profile for the eye and applying or prescribing the aberration profile. The wavefront aberration profile includes at least one spherical aberration term, wherein the prescription focal distance of the wavefront aberration profile is determined taking into account said spherical aberration. At the prescription focal distance the wavefront aberration profile provides an improving retinal image quality in the direction posterior to the retina.

In some embodiments a computational device includes an input to receive first combination of aberrations, one or more processors to compute a second combination of aberrations for one or more optical surfaces, and an output to output the second combination of aberrations, wherein the computed second combination of aberrations provides in combination with the first combination of aberrations a total combination of HOA as described above.

Further embodiments will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are schematic representations of eyes exhibiting myopia, hyperopia and astigmatism respectively.

FIGS. 2A and 2B are schematic representations respectively of hyperopic defocus and myopic defocus induced at the retina.

FIG. 3 shows a two-dimensional through-focus point spread function computed at the retinal plane without higher order aberrations (HOA) and in the presence of HOA of spherical aberration, vertical coma and horizontal trefoil.

FIGS. 4 to 7 show graphs of the interaction of primary spherical aberration with horizontal coma, vertical coma, horizontal trefoil and vertical trefoil respectively.

FIG. 8 shows a graph indicating the magnitude of myopia progression under an optical feedback mechanism for eye growth, for primary spherical aberration vs. primary vertical astigmatism vs. primary horizontal astigmatism.

FIG. 9 shows a graph indicating the magnitude of myopia progression for primary spherical aberration vs. secondary vertical astigmatism vs. secondary horizontal astigmatism.

FIG. 10 shows a graph indicating the myopia progression on a binary scale for primary spherical aberration vs. secondary spherical aberration.

FIG. 11 shows a graph indicating the myopia progression on a binary scale for primary spherical aberration vs. tertiary spherical aberration.

FIG. 12 shows a graph indicating the myopia progression on a binary scale for primary spherical aberration vs. quaternary spherical aberration.

FIG. 13 shows a graph indicating the myopia progression on a binary scale for primary spherical aberration vs. secondary spherical aberration vs. tertiary spherical aberration.

FIG. 14 shows example designs of aberration profiles that provide negative and positive gradient RIQ in a direction of eye growth.

FIG. 15 shows a work flow chart for myopic eyes, progressing or non-progressing.

FIG. 16 shows a work flow chart for hyperopic eyes, progressing or non-progressing towards emmetropia.

FIGS. 17 to 25 show example designs of power profiles of correcting lens across the optic zone diameter, for affecting optical feedback mechanisms for myopia.

FIG. 26 shows an example design of a power profile of correcting lens across the optic zone diameter, for affecting optical feedback mechanisms for hyperopia.

FIG. 27 shows a global through-focus retinal image quality (Q) for an aberration profile corresponding to a single vision lens.

FIG. 28 shows a global through-focus retinal image quality for a first aberration profile Iteration A1), which may have application to a progressing myopic eye, and FIG. 29 shows the power profile for a lens for providing the first aberration profile.

FIG. 30 shows a global through-focus retinal image quality for a second aberration profile (Iteration A2), which may also have application to a progressing myopic eye.

FIGS. 31 and 32 show a global through-focus retinal image quality for a third and fourth aberration profile (Iteration C1 and Iteration C2), which may have application to a hyperopic eye.

FIG. 33 show a retinal image quality (Q) for seven aberration profiles over a through focus range of 2.5 D. The seven aberration profiles correspond to example centre-distance and centre-near aspheric multifocals and concentric ring/annulus type bifocals and three exemplary aberration profiles (Iteration B1, Iteration B2, Iteration B3) for optimising through focus performance.

FIGS. 34 to 40 show the power profiles of contact lenses across the optic zone diameter, for providing the aberration profiles of FIG. 33.

FIGS. 41 to 43 show the on-axis through-focus image quality for the three exemplary embodiments for presbyopia (Iteration B1, B2 and B3) across four pupil diameters (3 mm to 6 mm) and FIGS. 44 and 45 show the on-axis through-focus image quality for the centre-distance and centre-near aspheric multifocal designs across four pupil diameters (3 mm to 6 mm).

FIGS. 46 and 47 show a monocular correction approach for presbyopia, where different higher order aberration profiles provided for the right and left eyes, by which the through-focus optical/visual performance is different in each eye (desired vergences) to provide a combined add power range of 1.50 D and 2.50 D, on the negative side of through-focus curve, respectively.

FIGS. 48 and 49 show a monocular correction approach for presbyopia, where different higher order aberration profiles provided for the right and left eyes, by which the through-focus optical/visual performance is different in each eye (desired vergences) to provide a combined add power range of 1.50 D and 2.50 D, on the positive side of through-focus curve, respectively.

FIG. 50 shows a global through-focus retinal image quality (Q) for three further iterations of aberration profile (Iterations A3, A4 and A5), for providing a relatively constant retinal image quality across a horizontal visual field from 0 to 30 degrees.

FIGS. 51 and 52 show example designs of the power profile of correcting contact lenses with opposite phase profiles (Iteration E1 and Iteration E2) and FIGS. 53 to 55 show the on-axis through-focus retinal image quality (Q) for Iterations E1 and E2 with three different levels of inherent primary spherical aberration.

FIG. 56 shows the through-focus RIQ performance measures (depth of focus) of 78 exemplary aberration profiles (Appendix A) that involve a combination of spherical aberration terms. The Y-axis in the graph denotes ‘Q’ performance metric and X-axis denotes the through-focus range from −1.50 to +1.00 D. All the calculations were performed at 4 mm pupil. The solid black line indicates the through-focus performance of a combination that does not have any mode of spherical aberration while all the gray lines indicate the 78 combinations which include at least one higher order spherical aberration term. The 78 combinations were selected with regard to performance on the negative side of the through-focus curve.

FIG. 57 shows the through-focus RIQ performance of one exemplary combination from FIG. 56 that involves only positive spherical aberration in comparison with a combination that has no spherical aberration.

FIG. 58 shows the through-focus RIQ performance measures (depth of focus) of 67 exemplary aberration profiles that involve a combination of spherical aberration terms (Appendix C). The Y-axis in the graph denotes ‘Q’ performance metric and X-axis denotes the through-focus range from −1.50 to +1.00 D. All the calculations were performed at 4 mm pupil. The solid black line indicates the through-focus performance of a combination that does not have any mode of spherical aberration while all the gray lines indicate the 67 combinations which include at least one higher order spherical aberration term. These 67 combinations improve performance on the positive side of the through-focus curve.

FIG. 59 shows a work flow chart for presbyopic eyes.

FIG. 60 shows a power profile for a toric prescription of a contact lens for both astigmatism and presbyopia.

FIG. 61 shows an example lens power profile, which is a combination of spherical aberration terms and FIG. 62 shows the lens power profile converted to an axial thickness profile for a contact lens.

DESCRIPTION OF EMBODIMENTS

The optical performance of the human eye is limited by a number of factors. Major factors include monochromatic and polychromatic optical wavefront aberrations, in addition to the retinal sampling which imposes a Nyquist limit on spatial vision. Minor factors include the Stiles-Crawford Effect and scattering. A quantitative measure of retinal image quality (RIQ) can be defined once all factors affecting image quality are quantified. A measure of RIQ may use a combination of factors that is a subset of all the factors that influence image quality.

1. Retinal Image Quality (RIQ)

With use of a wavefront aberrometer, such as a Hartmann-Shack instrument, the optical characteristics of a candidate eye can be measured so as to identify a measure of retinal image quality (RIQ). Several measures of RIQ are described below.

(A) Strehl Ratio

Once the wavefront aberration of the candidate eye is availed, the image quality at the retina of the eye can be determined by computing the simple Strehl ratio, as described in the Equation 1. The Strehl ratio can be computed in both spatial domain (i.e. using Point spread function) and in Fourier domain (i.e. using Optical transfer function as shown below in equation 1). The Strehl ratio measure is always bound between 0 and 1, where 1 is associated with best image quality.

$\begin{matrix} {{{Strehl}^{\prime}s\mspace{14mu}{ratio}} = \frac{\int{\int_{- \infty}^{+ \infty}\left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right)}}{\int{\int_{- \infty}^{+ \infty}\left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{{Wdiff}\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right)}}} & {{Equation}\mspace{14mu} 1} \end{matrix}$

(B) Visual Strehl Ratio

U.S. Pat. No. 7,077,522 B2 (Williams), which is hereby incorporated by reference herein in its entirety, describes a vision metric called the sharpness metric, by taking into account both the wavefront aberration and the retinal response to the image. This metric can be computed by convolving a point spread function with a neural quality function. Further, U.S. Pat. No. 7,357,509 B2 (Williams et al 2008) describes several other metrics to gauge optical performance of the human eye.

One such RIQ measure is the Visual Strehl Ratio, which calculated in the frequency domain. The Visual Strehl Ratio in the frequency domain is described by Equation 2 and is always bound between 0 and 1, where 1 is associated with best image quality at the retina. This metric only considers monochromatic aberrations.

$\begin{matrix} {{{monochromatic}\mspace{14mu}{RIQ}} = \frac{\begin{matrix} {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*{real}}}} \\ \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \end{matrix}}{\ \begin{matrix} {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*}}} \\ \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{{Wdiff}\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \end{matrix}}} & {{Equation}\mspace{14mu} 2} \end{matrix}$

The RIQ measure of monochromatic Visual Strehl Ratio shows high correlation with objective and subjective visual acuity (e.g. Thibos et al. Journal of Vision 2004). This measure has been predominantly been used to describe RIQ in the remainder of this specification. However, other measures described herein and alternatives thereto may be used in the design of optical devices, lenses and methods.

(C) Polychromatic RIQ

The Visual Strehl Ratio defined by Williams, discussed above, is limited to monochromatic light. To accommodate for polychromatic light, a metric called the polychromatic retinal image quality (polychromatic RIQ) is defined that includes chromatic aberrations weighed with spectral sensitivities for selected wavelengths. The polychromatic RIQ measure is defined in Equation 3.

$\begin{matrix} {{{polychromatic}\mspace{14mu}{RIQ}} = \frac{\begin{matrix} {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*{\sum\limits_{\lambda\mspace{11mu}\min}^{\lambda\;\max}\;\left( {{S(\lambda)}*} \right.}}}} \\ \left. \left( {{real}\left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2\pi\;{\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right)} \right) \right) \end{matrix}}{\begin{matrix} {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*{\sum\limits_{\lambda\mspace{11mu}\min}^{\lambda\;\max}\;\left( {{S(\lambda)}*} \right.}}}} \\ \left. \left( \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2\pi\;{\mathbb{i}}}{\lambda}*{{Wdiff}\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \right) \right) \end{matrix}}} & {{Equation}\mspace{14mu} 3} \end{matrix}$

(D) Monochromatic Global RIQ

The Visual Strehl Ratio or monochromatic RIQ discussed above in sub-section B is limited to on-axis vision. As used herein, unless the context clearly requires otherwise, ‘on-axis’ is a reference to any one of the optical, visual or papillary axis. To accommodate for wide angle view (i.e. peripheral visual field), a metric called the global retinal image quality (GRIQ) is defined that includes range of visual field eccentricities. A monochromatic GRIQ measure is defined in Equation 4.

$\begin{matrix} {{{monchromatic}\mspace{14mu}{Global}\mspace{14mu}{RIQ}} = \frac{\begin{matrix} {\int_{\alpha\;\min}^{\alpha\;\max}\int_{\varphi\;\min}^{\varphi\;\max}} \\ {{\begin{Bmatrix} {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*{real}}}} \\ \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2\pi\;{\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \end{Bmatrix}{\mathbb{d}\varphi}{\mathbb{d}\lambda}}\ } \end{matrix}}{\begin{matrix} {\int_{\alpha\;\min}^{\alpha\;\max}\int_{\varphi\;\min}^{\varphi\;\max}} \\ {{\begin{Bmatrix} {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*}}} \\ \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2\pi\;{\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \end{Bmatrix}{\mathbb{d}\varphi}{\mathbb{d}\lambda}}\ } \end{matrix}}} & {{Equation}\mspace{14mu} 4} \end{matrix}$

(E) Polychromatic Global RIQ

One other form of RIQ metric that accommodates for polychromatic light and wide angle view (i.e. peripheral visual field), a metric is called the polychromatic global retinal image quality (GRIQ) is defined that includes chromatic aberrations weighed with spectral sensitivities for selected wavelengths and range of visual field eccentricities. A polychromatic GRIQ measure is defined in Equation 5.

$\begin{matrix} {{{polychromatic}\mspace{14mu}{Global}\mspace{14mu}{RIQ}} = \frac{\begin{matrix} {{\int_{\alpha\;\min}^{\alpha\;\max}\int_{\varphi\;\min}^{\varphi\;\max}}\ } \\ \begin{matrix} \left\{ {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*{\sum\limits_{\lambda\;\min}^{\lambda\;\max}\;\left( {{S(\lambda)}*} \right.}}}} \right. \\ {\left. \left. \left( {{real}\left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right)} \right) \right) \right\}{\mathbb{d}\varphi}{\mathbb{d}\lambda}} \end{matrix} \end{matrix}}{\begin{matrix} {{\int_{\alpha\;\min}^{\alpha\;\max}\int_{\varphi\;\min}^{\varphi\;\max}}\ } \\ \begin{matrix} \left\{ {\int{\int_{- \infty}^{+ \infty}{{{CSF}\left( {f_{x},f_{y}} \right)}*{\sum\limits_{\lambda\;\min}^{\lambda\;\max}\;\left( {{S(\lambda)}*} \right.}}}} \right. \\ {\left. \left. \left( \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{{Wdiff}\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \right) \right) \right\}{\mathbb{d}\varphi}{\mathbb{d}\lambda}} \end{matrix} \end{matrix}}} & {{Equation}\mspace{14mu} 5} \end{matrix}$

In Equations 1 to 5:

-   -   f specifies the tested spatial frequency, this can be in the         range of F_(min) to F_(max) (denoting the boundary limits on the         spatial frequency content), for example F_(min)=0 cycles/degree;         F_(max)=30 cycles/degree;     -   f_(x) and f_(y) specifies the tested spatial frequency in x and         y directions;     -   CSF (f_(x), f_(y)) denotes a contrast sensitivity function,         which in a symmetric form can be defined as CSF         (F)=2.6(0.0192+0.114*f)*exp^(−(0.114)*^(f)^1.1);     -   FT denotes, in one form of the equation, a 2D fast Fourier         transform;     -   A(ρ, θ) and W(ρ, θ) denotes pupil diameter & wavefront phase of         the test case, respectively;     -   Wdiff (ρ, θ) denotes wavefront phase of the diffraction limited         case;     -   ρ and θ are normalised polar coordinates, where ρ represents the         radial coordinate and θ represents the angular coordinate or the         azimuth;     -   λ denotes wavelength;     -   α denotes field angle;     -   φ denotes the meridian angle;     -   S (λ) denotes spectral sensitivity.

The wavefront phase, for example, can be written as a function set of standard Zernike polynomials up to a desired order, as described below,

${W\left( {\rho,\theta} \right)} = {\sum\limits_{i = 1}^{k}\;{\alpha_{i}{Z_{i}\left( {\rho,\theta} \right)}}}$

Where, α_(i) denotes the i^(th) coefficient of Zernike polynomial

-   -   Z_(i)(ρ, θ), denotes the i^(th) Zernike polynomial term     -   ‘k’, represents the highest term of the expansion

These polynomials can be represented in the Optical Society of America format or Malacara format or other available Zernike polynomial expansion formats. Apart from the Zernike method of constructing the wavefront phase, any other non-Zernike method of wavefront phase construction can also be adopted i.e. Fourier expansion, Taylor expansion, etc.

(F) Global RIQ Metric Integrated Myopic Impetus Exposure Time

All the factors included in the above RIQ variants include wavefront aberration, chromaticity and spectral sensitivity, Stiles-Crawford Effect of the first kind, and optical/visual performance in the peripheral retina. Another factor that can be included is the amount of time spent at various accommodative states on an average day (the daily amount of near work), also known as the myopic impetus exposure time, T (A). This provides the following GRIQ variant:

$\begin{matrix} {\int_{Amin}^{Amax}{{T(A)}*{{GRIQ}\ \left( {\mathbb{d}A} \right)}}} & {{Equation}\mspace{14mu} 6} \end{matrix}$

(G) Other Possible RIQ Measures

As mentioned above, other measures of RIQ proposed can also be used in the design of devices, lenses and methods. One example of an alternative RIQ measure is simple modulation transfer function (MTF). Referring to Equation 2, a polychromatic MTF is formed by computing the modulus of real part of the optical transfer function and in addition excluding the step of convolution with the CSF function. A monochromatic MTF is formed if S (λ) is also removed from Equation 2.

2. Through Focus RIQ

RIQ may also be considered anterior and/or posterior to the retina. The RIQ anterior and/or posterior to the retina is called ‘through focus RIQ’ herein. Similarly, RIQ at and/or around the retina may also be considered over a range of focal lengths (i.e. when the eye accommodates, which causes refractive characteristics of the eye in addition to the focal length to change).

Embodiments consider not only RIQ at the retina, but also the change in through focus RIQ. This is in contrast to an approach that may, for example, consider only the RIQ at the retina and/or an integral or summation of RIQ measures at or around the retina. For example, embodiments of the lenses, devices and methods described herein effect, or are designed to effect for an eye with particular refractive characteristics, a change in or control over the extent or rate of change in RIQ in the directions anterior to the retina (i.e. the direction from the retina towards the cornea) and/or posterior to the retina.

Embodiments also effect, or are designed to effect a change in or control over the variation in RIQ with focal distance. For example several candidate lens designs may be identified through effecting a change in the retinal image quality in the direction posterior to the retina and then a single design or subset of designs may be identified taking account of variation in RIQ with change in focal length.

In other embodiments the process described above is reversed. In particular, a set of designs is selected based on changes in RIQ at the retina with focal distance. Selection within the set is then made with reference to the through focus RIQ.

In still other embodiments a single evaluation process is conducted that combines consideration of through focus RIQ and changes of RIQ at the retina with a said focal distance. For example, an average measure of RIQ with changes in focal distance may be used to identify a design. The average measure may give more weight to particular focal distances (e.g. distance vision, intermediate vision and near vision and therefore may be weighted differently),

In various embodiments, through focus and/or changes of RIQ at the retina with focal distance are considered: i) on-axis, ii) integrated around on-axis, for example in an area corresponding to or approximating a pupil size, with or without consideration of the Stiles-Crawford effect, iii) off-axis (where off-axis means a location, set of locations or integral of locations on the retina outside the fovea, which may be where light at field angles more than about 10 degrees is focussed), and/or iv) for a combination of i) to iii).

While the description herein refers predominantly to quantitative measures of RIQ, qualitative measures may be used in the design process of an aberration profile instead or in addition to the quantitative measures. For example, the Visual Strehl Ratio at a particular through focus location is computed based on the point spread function. As can be seen from the example images referred to in the following section, the point spread function can be visually evaluated. This provides for a method of qualitatively evaluating through focus.

3. Aberrations Affecting Image Quality at the Retina and Through Focus RIQ

The influence of lower order aberrations on retinal image quality and through focus RIQ is well understood. The use of corrective lower order aberrations represents a traditional method of refractive error correction for an eye. Accordingly, the identification of an aberration profile consisting of lower order aberrations to correct for defocus and astigmatism will not be described herein in detail.

The influence of higher order aberrations (HOA) on image quality can be appreciated from the through-focus two-dimensional point spread functions 300 illustrated in FIG. 3. In FIG. 3 the rows show the point spread functions for a selection of aberrations and the horizontal axis shows the extent of defocus for the relevant aberration, in Diopters.

The point spread functions without any higher order aberrations 302 (in the illustrated example images at the retina in an eye with myopia or hyperopia alone), with vertical coma 306 alone, and with horizontal trefoil 308 alone, remain symmetrical with positive and negative defocus. With positive and negative primary spherical aberrations, either alone 304 or in combination 310 with coma and/or trefoil, the through-focus in the point spread function is asymmetrical for positive and negative defocus. With certain HOA positive and negative defocus has unequal effects on the image quality. It can be seen that these unequal effects are more pronounced for spherical aberrations. The HOA that exhibit asymmetrical effects on RIQ, visual acuity and/or contrast sensitivity have particular application to the lenses, devices and methods disclosed herein.

The interactions occurring between HOA and defocus influence the through-focus RIQ. Some HOA interact favourably with defocus to improve RIQ, while others interact unfavourably to cause RIQ degradation. The most commonly measured higher order ocular aberrations include spherical aberration, coma and trefoil. Apart from these, the HOA profiles obtained with some multifocal optical designs precipitate considerable magnitudes of wavefront aberrations, often expressed up to the 10th order in Zernike polynomial representation.

Generally, in the Zernike pyramid, the terms closer to the centre are often more influential when gauged in terms of the resultant optical effects than those at the edge/corner. This may be because the terms farther away from the centre have a relatively large planar area on the wavefront compared to those whose angular frequency is closer to zero. Accordingly, Zernike terms that have the highest potential to interact with defocus are, for example, the terms with even radial order having zero angular frequency component, i.e. the fourth, sixth, eighth, and tenth order Zernike coefficients, representing primary, secondary, tertiary and quaternary, spherical aberrations.

The foregoing description of aberrations identifies some of the aberrations that affect retinal RIQ and through focus RIQ. The description is not, nor is it intended to be, an exhaustive description of all aberrations that affect retinal RIQ and through focus RIQ. In various embodiments additional aberrations that affect the retinal RIQ and/or through focus RIQ may be considered, the relevant aberrations being identified having regard to the current refractive state of the ocular system (meaning the eye together with any lenses or optical devices that affect the wavefront received by the retina) and a target retinal RIQ/through focus RIQ.

4. Optimising RIQ

When designing or selecting a required change in refractive state of an eye a measure of RIQ and through focus RIQ is required. In particular, finding a magnitude and sign of defocus of the relevant aberrations that produces an acceptable RIQ and through focus RIQ is required. The search is for the best or at least an acceptable combination of RIQ and through focus RIQ. In some embodiments described herein, a merit function S=1/RIQ is used for this purpose.

Identifying aberration coefficients that optimise RIQ at the retina may be achieved by finding a minimum value of the function S. Considering this in combination with through focus RIQ adds complexity to the optimisation process. Various methods can be used to address this complexity.

One example is to use a non-linear, unconstrained optimization routine, over the chosen group of Zernike SA coefficients as variables. A random element, either automatic or through human intervention may be incorporated to shift to different locations so as to find alternative local minima of the function S. The criteria by which the optimisation routine evaluates performance may be a combination of retinal RIQ and keeping the through focus RIQ within predefined bounds of the retinal RIQ. The bounds may be defined in various ways, for example as a range about the value for retinal RIQ. The range may be fixed (e.g. plus or minus 0.15 for Visual Strehl ratio or GRIQ or similar measure), or may vary (e.g. be within a defined rate of change with increasing distance from the retina). As explained in more detail herein below, the objective range for through focus RIQ may change depending on whether the objective is to provide a sloped through focus RIQ so as to provide stimulus to inhibit or encourage eye growth under an optical feedback explanation of emmetropisation, or to provide a flat through focus RIQ.

Another approach is to limit the number of possible aberration profiles. One way of limiting the possible aberration values is to specify that the Zernike coefficients can only have values corresponding to increments of 0.05 μm focus, or another increment interval. The interval can be selected having regard to the available computational resources. By limiting the number of allowable coefficient values it is possible to simulate the performance of all aberration profiles formed by the combinations of Zernike coefficients, following which those with the best or acceptable on-axis RIQ and through focus RIQ can be identified. The results of this process may be used to constrain more fine-tuned analysis, for example by returning to an optimisation routine with coefficient values within a small range around an identified candidate combination.

5. Controlling Stimulus for Refractive Error Progression by Optical Feedback

In some embodiments a lens, device or method that incorporates an aberration profile to provide a particular on-axis RIQ and through focus RIQ is applied to an eye with progressing myopia or an eye identified as at risk of developing myopia. A person may be identified as being at risk of developing myopia based on a number of indicators, including whether their parents experienced myopia/progressing myopia, their ethnicity, lifestyle factors or otherwise. A person may be identified as being at risk of developing myopia if their eye(s) have an RIQ that improves in the direction of eye growth (when eye growth is not required), either with or without any correction that is currently being used (e.g. with or without a current prescription of lens). The use of improving RIQ in the direction of eye growth may be used alone or in conjunction with other indicators, for example the other indicators listed above.

Under an optical feedback mechanism explanation of emmetropisation based on RIQ, the eye is stimulated to grow to the position where the merit function S is minimised. Under this explanation of emmetropisation, for human eyes, if the location of the minimum of the function S (which may be a local minimum) is posterior to the retina or if through focus RIQ improves posterior to the retina, the eye will be stimulated to grow longer and if this location is on or anterior to the retina, then the eye will remain at the same length. The lenses, devices and methods disclosed herein may be applied to provide stimulus under this optical feedback mechanism explanation of emmetropisation. Embodiments for addressing eye growth under the optical feedback explanation of emmetropisation (e.g. to address myopia progression or to seek to stimulate eye growth to correct hyperopia) use aberrations to affect one or both of the location of the minima of the function S relative to the retina and the gradient of the function S through the retina.

The following description describes how combinations of selected HOA can affect a change in a measure of through focus RIQ. Each of these aberrations can readily be incorporated into a lens, optical device or used in a method of changing the aberration profile of light received by the retina. This provides a mechanism by which a lens, optical device or method of changing the refractive state of an eye (e.g. refractive surgery) can be designed or selected to obtain a target through focus RIQ for an eye, or at least change the refractive state of the eye to closer to a target through focus RIQ. As described in more detail below, achieving a target through focus RIQ is considered together with achieving or getting closer to a target on-axis RIQ at the retina for particular focal length, which is typically distance vision (objects at infinity or practically for human eyes, greater than 3 meters to about 6 meters), but which may be another selected focal length, for example intermediate vision (e.g. about 0.75-2 meters) or near vision (e.g. about 0.35 to 0.60 meters).

For the examples described below the RIQ was evaluated using the Visual Strehl Ratio shown in Equation 2.

(A) Primary Spherical Aberration, Coma and Trefoil

The interactions between primary spherical aberration, coma and trefoil and their affect on eye growth can be described using a wavefront phase function defined using defocus, primary spherical aberration (PSA), coma and trefoil terms of a standard Zernike expansion.

The pupil size was fixed at 4 mm and the calculations were performed at 589 nm wavelength. For the purposes of evaluating affects of aberration profiles on ocular growth, it was assumed that a location of a minimum of the above described function S posterior to the retina provides a stimulus to grow to that location and that there will not be stimulus for eye growth if the minimum of the function S is on or in front of the retina. In other words, it is assumed that the image formed on the retina provides a stimulus to grow to minimise the function S. The range of values of PSA, horizontal and vertical coma, and horizontal and vertical trefoil that were used in the simulations are:

PSA=(−0.30, −0.15, 0.00, 0.15, 0.30) μm

Horizontal Coma=(−0.30, −0.15, 0.00, 0.15, 0.30) μm

Vertical Coma=(−0.30, −0.15, 0.00, 0.15, 0.30) μm

Horizontal Trefoil=(−0.30, −0.15, 0.00, 0.15, 0.30) μm and

Vertical Trefoil=(−0.30, −0.15, 0.00, 0.15, 0.30) μm.

With a total of 3125 combinations tested, overall it was observed that spherical aberration primarily governed the direction of improving RIQ.

FIGS. 4 to 7 illustrate the stimulus for eye growth resulting from through-focus RIQ for a selection of the combinations, in particular the combined effects of PSA together with horizontal and vertical coma, and together with horizontal and vertical trefoil. FIGS. 4 to 7 are on a continuous scale and white (0) indicates no progression and gray-to-black transition indicates the amount of progression in Diopters.

FIG. 4 shows a graph 400 of the interaction of primary spherical aberration and horizontal coma. The gray plot indicates the amount of progression of myopia that is stimulated by the combination of these two aberrations, where white 402 indicates no stimulus for progression and shades towards black 404 indicate stimulus for progression of myopia (in this case up to −0.8 D) as a result of PSA combined with horizontal coma. FIG. 5 shows a graph 500 of myopia progression as a function of the interaction of primary spherical aberration and vertical coma. Like in FIG. 4, white areas 502 indicate no stimulus for progression and dark areas 504 indicate stimulus for progression. FIG. 6 shows a graph 600 of the interaction of primary spherical aberration and horizontal trefoil. FIG. 7 shows a graph 700 of myopia progression as a function of the interaction of primary spherical aberration and vertical trefoil. For the combinations shown in FIGS. 4 to 7, about 52% of the combinations provide stimulus to encourage eye growth.

The above described stimulus for eye growth may accordingly be removed by controlling the refractive state of an eye to be within any of the white areas in FIGS. 4 to 7. This may be achieved, for example, by designing a lens or optical device that when applied modifies the refractive characteristics of the eye, to result in the retina of the eye experiencing a through focus RIQ that does not improve in the direction of eye growth (posterior to the retina) or which decreases in the direction of eye growth.

Although trefoil and coma in the range of −0.30 to 0.30 μm over a 4 mm pupil do not appear to have a significant impact on the direction of growth (the maximum progression effect is only −0.1 D), positive PSA seems to accelerate growth while negative PSA inhibits growth. The PSA therefore appears to have the dominant effect. Accordingly, at least for an eye with positive PSA and optionally one of coma and trefoil, adding negative PSA will inhibit eye growth under the optical feedback explanation of emmetropisation. It follows that providing negative PSA to an eye, or at least removing positive PSA may remove the stimulus for eye growth. Any coma and trefoil in the eye may be left unchanged or optionally partially or fully corrected (preferably within the range of −0.30 to 0.30 μm).

(B) Spherical Aberration and Astigmatism

To illustrate the interactions between primary spherical aberration and astigmatism, a wavefront phase function was defined using these aberrations (including both horizontal/vertical and oblique components) and defocus. FIGS. 8 to 13 (unlike FIGS. 4 to 7) are on a binary scale—where white (1) indicates test cases that cause stimulus for progression (i.e. increase in ocular growth) and black (0) indicates candidate combinations that result in no progression (i.e no ocular growth stimulus or a stop signal). The scale has no units.

FIG. 8 shows a graph 800 indicating the magnitude of myopia progression for PSA vs. a primary oblique astigmatic component (POA) vs. a primary horizontal/vertical astigmatic (PHV) component. The graph 800 indicates those combinations of PSA and astigmatism that will result in stimulus for myopia progression (white) and those combinations that will not result in stimulus for myopia progression (black). Neither POA nor PHV appear to have a significant impact on the effects of PSA.

FIG. 9 shows a graph 900 indicating the magnitude of myopia progression for PSA vs. a secondary oblique astigmatic (SOA) component vs. a secondary horizontal/vertical astigmatic (SHV) component. Neither SOA nor SHV appear to have a significant impact on the effects of PSA.

A stimulus for eye growth may accordingly be removed by controlling the refractive state of an eye to be within any of the white areas in FIGS. 8 and 9.

From FIGS. 8 and 9, the primary and secondary astigmatic components have a small influence on enhancing or inhibiting eye growth, when combined with PSA. Accordingly, considering these aberrations, this indicates priority should be provided to PSA. In addition, it may be determined whether the eye has high levels of POA, PHV, SOA and/or SHV. If this is the case, then correcting these aberrations (by reducing or substantially eliminating them) may also assist in removing stimulus for eye growth.

(C) Higher Order Spherical Aberrations

For unaided or single-vision spectacle corrected eyes a fourth order Zernike expansion is generally sufficient to describe the wavefront at the exit pupil. However, this is not necessarily the case when contact lenses are used for correction, especially with multifocal contact lenses (both aspheric and concentric), substantial amounts of fifth order and higher HOA may be imposed. Multifocal contact lenses may for example be described using up to about the tenth or twentieth order of Zernike polynomials. In such cases the magnitudes and signs of the higher order spherical aberrations start to play a significant role (in addition to PSA).

To illustrate the interactions between primary, secondary, tertiary and quaternary spherical aberrations of a standard Zernike expansion, a wavefront phase was defined using these terms and defocus. Several combinations of HOA as predicted from modelled data with such multifocal contact lenses were used. Selective sets of these HOA that demonstrate interactions to produce peak RIQ were obtained via dedicated non-linear optimization routines. All the calculations were performed over a 4 mm pupil, and at 589 nm wavelength. It was observed that at least the first three modes of spherical aberration of the inherent eye played a significant role in governing the direction of stimulus for eye growth and in some cases higher modes of spherical aberration also played a significant role.

The results described below relate to secondary spherical aberration (SSA), tertiary spherical aberration (TSA) and quaternary spherical aberration (QSA), but spherical aberrations with higher orders may also be used in embodiments of the lenses, devices and methods described herein. For all four types of spherical aberrations, a range from −0.30 to 0.30 μm was used to investigate the effects of the combinations of HOA. These ranges for these types of aberrations do not necessarily accord with normative distributions of aberrations associated with eyes because the occurrence of these higher order aberrations are not necessarily associated with the eyes but with the optical devices (such as multifocal contact lenses) alone or in combination with the eyes. Furthermore, the range from −0.30 to 0.30 μm is merely used to illustrate the effects, but when determining combinations of HOA to provide an aberration profile in a lens or optical device, or to be effected by surgical procedures, larger or smaller ranges may be used.

FIGS. 10 to 12 show the stimulus for myopia progression as a function of PSA together with SSA, TSA and QSA respectively. This schema is a binary colour plot, where white (0) indicates wavefront aberration combinations that provide stimulus for myopia progression under the feedback mechanism described above and black (1) indicates combinations that discourage myopia progression. From these graphs it is apparent that the higher orders of spherical aberrations have an impact on the stimulus for progression of myopia. About 82% of the combinations investigated suggest stimulus for eye growth. Interactions of the spherical aberration terms depend on their individual signs and then their individual magnitudes.

FIG. 10 shows a graph 1000 indicating the presence of stimulus for myopia progression as a function of combinations of PSA and SSA. In FIG. 10, it can be seen that when PSA in the range −0.30 μm to 0.20 μm is combined with negative SSA ranging from 0.00 to −0.30 μm, there is no improvement of RIQ in the direction of eye growth, thus no myopia progression is predicted (i.e. in the area indicated 1004). However, when PSA ranging from 0.20 to 0.30 μm is considered with negative SSA of about −0.10 μm, it seems to aggravate the progression, as indicated in the area 1002. Overall, the sign of SSA seems to have a governing effect on the effect of the wavefront aberrations and the resultant retinal image quality. Negative SSA of considerable magnitudes (i.e. greater than −0.20 μm) predicts a protective effect against myopia progression when combined with either positive or negative PSA, when PSA and SSA are the only two HOA involved in the wavefront aberration of the candidate eye.

FIG. 11 shows a graph 1100 indicating the presence of stimulus for myopia progression as a function of combinations of PSA and TSA. When PSA and TSA have the same sign and TSA is about ⅘th of PSA in magnitude, as indicated by rectangular box 1106, no or little myopia progression is predicted (black area). However, with other combinations of PSA and TSA, for example as indicated in areas 1102 and 1104, myopia progression can be expected.

FIG. 12 shows a graph 1200 indicating the presence of stimulus for myopia progression as a function of combinations of PSA and QSA. When PSA and QSA have opposite signs and QSA is about ⅘th of PSA in magnitude, as indicated by the predominantly black area 1204, no myopia progression is predicted. However, with other combinations of PSA and QSA, (for example as indicated in white areas 1202 and 1206) myopia progression can be expected.

FIG. 13 is a graph (1300) showing the presence of stimulus for progression of myopia as a function of PSA, SSA and TSA. This schema is a binary colour plot, where 1 (white) indicates wavefront aberration combinations that favour myopia progression; while 0 (black) indicates combinations that discourage myopia progression (i.e. do not provide stimulus for eye growth).

The majority of the black filled circles 1304 are in the region governed by negative SSA, with a few exceptions. Further, combinations in which PSA and TSA have the same sign coupled with negative SSA seem to provide a protective effect against myopia progression. The combinations of PSA, SSA, TSA and QSA that have a protective effect against myopia progression under the optical feedback explanation of emmetropisation (which include the black areas shown in FIG. 13) can be summarised as shown in the Table 1.

TABLE 1 Combination sets of higher order aberrations which discourage the eye growth (i.e potential treatment for myopia). Specific higher order aberration in addition to Magnitude and sign of the SNo defocus higher order aberration 1 PSA only −0.30 μm <= PSA < 0.125 μm 2 SSA only −0.30 μm <= SSA <= 0.075 μm 3 TSA only −0.30 μm <= TSA <= 0.075 μm 4 QSA only −0.10 μm <= QSA <= 0.075 μm 5 PSA & SSA −0.30 μm <= PSA <= 0.20 μm and −0.25 μm <= SSA <= 0.025 μm 6 PSA & TSA −0.30 μm <= PSA <= 0.30 μm and TSA = (PSA/2)μm +/− 0.075 μm 7 PSA & QSA −0.30 μm <= PSA <= 0.30 μm and QSA = (|PSA|/3) μm +/− 0.075 μm 8 PSA, SSA, TSA −0.30 μm <= PSA < −0.05 μm & 0.05 μm < PSA < 0.30 μm; −0.30 μm <= SSA < 0.05 μm; −0.20 μm <= TSA < −0.025 μm & 0.025 μm < TSA < 0.20 μm; 9 PSA, SSA, TSA and QSA −0.30 μm <= PSA < −0.05 μm & 0.05 μm < PSA < 0.30 μm; −0.30 μm <= SSA < 0.05 μm; −0.20 μm <= TSA < −0.025 μm & 0.025 μm < TSA < 0.20 μm; −0.20 μm <= QSA < −0.025 μm & 0.025 μm < QSA < 0.20 μm;

The majority of the white circles 1302 are in the region governed by positive SSA, with a few exceptions. Further, combinations in which the PSA and TSA have the same sign coupled with positive SSA may provide a treatment effect for hyperopia. The combinations of PSA, SSA, TSA and QSA that have a treatment effect against hyperopia under the optical feedback explanation of emmetropisation (including the white areas shown in FIG. 13) can be summarised as shown in the Table 2.

TABLE 2 Combination sets of higher order aberrations which encourage eye growth (i.e potential treatment for hyperopia). Higher order aberration Magnitude and sign of the SNo in addition to defocus higher order aberration 1 PSA only 0.30 μm => PSA >= 0.125 μm 2 SSA only 0.30 μm => SSA > 0.075 μm 3 TSA only 0.30 μm => TSA > 0.075 μm 4 QSA only −0.30 μm <= QSA <= −0.125 μm or 0.30 μm => QSA > 0.075 μm 5 PSA & SSA −0.30 μm <= PSA <= 0.30 μm and 0.30 μm >= SSA > 0.075 μm 6 PSA & TSA −0.30 μm <= PSA <= 0.30 μm and (PSA/2) μm + 0.075 μm <= TSA < 0.30 μm or −0.30 μm <= TSA < (PSA/2) μm − 0.075 μm 7 PSA & QSA −0.30 μm <= PSA <= 0.30 μm and QSA in the range −0.20 to 0.20 μm but excluding values where QSA = (|PSA|/3) μm +/− 0.075 μm 8 PSA, SSA, TSA −0.30 μm <= PSA < −0.05 μm & 0.05 μm < PSA < 0.30 μm; 0.075 μm <= SSA < 0.30 μm; −0.20 μm <= TSA < −0.025 μm & 0.025 μm < TSA < 0.20 μm; 9 PSA, SSA, TSA and QSA −0.30 μm <= PSA < −0.05 μm & 0.05 μm < PSA < 0.30 μm; 0.075 μm <= SSA < 0.30 μm; −0.20 μm <= TSA < −0.025 μm & 0.025 μm < TSA < 0.20 μm; −0.20 μm <= QSA < −0.025 μm & 0.025 μm < QSA < 0.20 μm;

Accordingly, when designing a lens, optical device or method of altering the eye, the aberrations may be selected to provide a combination of the aforementioned aberrations that provide for either a protective effect against eye growth, or which encourage eye growth. The combination of aberrations may be applied in combination with the required correction of any myopic defocus or hyperopic defocus.

From the foregoing description, it is apparent that the spherical aberration terms, including the primary, secondary, tertiary and quaternary SA terms influence RIQ and through focus RIQ. In addition, it has been found that much higher orders of spherical aberration also influence RIQ and through focus RIQ. Accordingly in various embodiments different combinations of spherical aberration are used, including embodiments using any combination of two or more spherical aberration terms that provide a required or acceptable through focus RIQ profile, together with a required or acceptable RIQ at a particular focal length (e.g. distance vision).

6. The Instantaneous Gradient of the Image Quality

The foregoing description of stimulus for eye growth under the optical feedback mechanism explanation of emmetropisation focussed on the location of the peak RIQ. Another approach is to consider the slope of through-focus RIQ at the retina. In some embodiments, methods and devices control or utilise this gradient of the image quality metric. The gradient may be considered for any measure of RIQ.

In the following description it is assumed that a positive measure of the gradient of the through-focus RIQ (increasing RIQ posterior to the retina) provides a stimulus for the development and progression of myopia, while a negative measure of the same retards or halts myopia progression.

FIG. 14 shows a plot of RIQ for two different cases, 1402 and 1404, as a function of through focus in the direction posterior to the retina. The cases are two different combinations of PSA, SSA and TSA that produce identical retinal RIQ. As can be seen from the figure, although both sets of selected aberrations produce similar image quality at the retina (defocus=0), with the introduction of defocus (in the direction of eye growth) the retinal image quality of test case 1402 ramps up indicating stimulus for eye growth, while test case 1404 indicates that there would be no stimulus for growth, as the retinal image quality degrades further in the direction of eye growth, i.e. positive Zernike defocus.

From the results described above that indicate the effects of HOA on image quality and the resulting progression of myopia, it is possible to determine the relevant HOA combinations that can be used in lenses, optical devices, or effected using optical surgery, which, where relevant in combination with the eye's aberrations, will result in the HOA combinations that inhibit or retard eye growth for the treatment of myopia progression. In order to slow down eye growth in myopia, compensating optical devices or surgical procedures can be used that, in combination with the optics of the eye, will result in a combination of HOA that results in a negative gradient of through-focus retinal image quality, as shown in example 1404 (FIG. 14). For treating hyperopia, compensating optical devices or surgical procedures can be used that, in combination with the optics of the eye, will result in a combination of HOA that results in a positive gradient of through-focus retinal image quality, as shown in example 1402 (FIG. 14).

If an aberration profile has a varying RIQ across a through focus range, then the slope of through focus RIQ at a particular focal length can be changed by selecting a suitable defocus term C(2,0) with the considered RIQ profile. For example, if the slope is positive at a first level of through focus and negative at a second level of through focus, the slope at the retina of a recipient eye can be selected by selectively introducing defocus at either the first or second level. Examples of aberration profiles that have varying RIQ slopes at different levels of defocus are provided below in relation to embodiments of aberration profiles for application to presbyopia. Many of the embodiments described for presbyopia may be applied to provide a stimulus to retard or encourage eye growth under the optical feedback explanation of emmetropisation described above. Typically, younger people have progressing myopia and as such they will not be experiencing presbyopia. Accordingly, the aberration profile selected may place less weight on achieving high RIQ over a large through focus range and more weight on achieving the highest RIQ at the retina for distance vision in combination with providing a negative slope RIQ profile through the retina (i.e. decreasing RIQ in the direction of eye growth). For the young hypermetropes, again, the selected aberration profile may place less weight on achieving high RIQ over a large through focus range and more weight on achieving the highest RIQ at the retina for distance in combination with provision of a positive slope of RIQ profile behind the retina (in the direction of eye growth).

In addition, the slope across a range of field angles can be considered and/or variations in the RIQ for a range of pupil sizes. For example, an aberration profile may be selected that provides an average, mode or substantially uniform slope across a range of field angles, such as 10, 20, 30 or 40 degrees that either inhibits or encourages eye growth (and/or cancel existing aberrations in the eye that encourage or inhibit eye growth respectively). The average slope across the range of pupil sizes or at the mode pupil size may also be considered. Alternatively, the design may be selected that has either a positive or negative slope of through focus RIQ for all field angles within a range and/or for all pupil sizes with a range.

7. Aberration Design or Selection Process

In some embodiments determining the aberration profile required in a lens, optical device or resulting from a procedure, includes first identifying the HOA present in the eye. Measurements may be taken, for example, using wavefront eye exams that use aberrometry such as with a Shack-Hartmann aberrometer. The eye's existing HOA may then be taken into account. In addition, any HOA effects inherent in the lenses or optical devices may also be taken into account.

When the requirement is for a lens that provides stimulus for eye growth or to retard eye growth, these existing HOA are then compared to HOA combinations that inhibit or retard myopia progression (for example as discussed above with reference to FIGS. 5 to 14) to determine one or more additional HOA that may be required to reduce or retard or encourage eye growth under the optical feedback mechanism of emmetropisation. These additional combinations are then implemented in the design of lenses or optical devices or implemented using optical surgery. Flowcharts in FIGS. 15 and 16 provide a summary of suitable methods.

Alternatively, the eye's existing aberrations may be disregarded and an aberration profile that provides the required through focus RIQ slope may be provided for the eye by a lens, preferably a removable lens so that different aberration profiles may be trialled if required. The aberration profile resulting from the combination of the aberration profile of the lens and the eye may then be measured to determine if the RIQ characteristics are acceptable (for example, provide a particular through focus RIQ slope and acceptable RIQ for distance vision). Alternatively, different lenses may be placed on the eye with measures of objective and/or subjective vision determining which lens to select. Where the lens is selected to provide stimulus inhibiting or encouraging eye growth without regard to the eye's existing aberrations, the selected aberration profile may be one with generally higher values of spherical aberration, so that the sign of the slope is not changed by lower level of HOA in the eye.

In other applications, the goal for the combination of HOA may be different. For example, when considering presbyopia the goal may be a combination of aberrations that provide high RIQ over a large through focus. Where peripheral vision is important, then the objective may include high RIQ over a large range of field angles. Accordingly, in various embodiments the HOAs are utilised to optimise for the goals of a combination of high RIQ at the retina and one or more of a low slope through focus RIQ, a low change in RIQ with pupil diameter and a high RIQ in the peripheral field.

The examples that follow have been selected using the RIQ measure in Equation 2. The initial set of designs for analysis was found by computing this RIQ for all combinations of SA Zernike coefficients up to the 10th order. Each coefficient was constrained to the range −0.3 μm to 0.3 μm and constrained to be a value that is a multiple of 0.025 μm.

An analysis of the initial set of designs included: 1) identifying optimised combinations of Zernike coefficients that provide a high RIQ and a negative slope through focus RIQ about the retina; 2) consideration of the RIQ and through focus RIQ and change in RIQ and through focus RIQ at different pupil sizes; and 3) consideration of the RIQ across the horizontal visual field. The relative weight given to these stages of evaluation may vary for the particular recipient. For the purposes of identifying the following examples, most weight was given to the first criteria.

8. Examples of Optical Designs Addressing the Slope of Through Focus RIQ

Examples of designs for affecting stimulus for eye growth under an optical feedback mechanism are provided herein below. The examples below are rotationally symmetric. However, astigmatic designs and other non-rotationally symmetric designs may be produced. When a deliberate decentration of the symmetric designs is imposed so that the optical axes of the correcting contact lens coincides with a reference axis of the eye say pupillary axis or visual axis, some residual amounts of asymmetric aberrations like coma and trefoil can be induced, these may be compensated by the choice of additional higher order asymmetric terms.

FIGS. 17 to 25 show the power profile graphs of sample designs that provide a RIQ that degrades in the direction of eye growth for on-axis vision (i.e. at zero field angle), thus providing a stimulus to inhibit eye growth under the optical feedback mechanism explanation of the emmetropisation process. The aberration profile graphs are described as the axial power variation in diopters across the optic zone diameter. All the examples provided may have application to a progressing myope whose spherical refractive error is −2.00 D and this information is indicated by a dual gray line on all the power profiles.

FIG. 26 shows the details of a sample design that could be used for hyperopia treatment. This designs was produced by taking a specific aberration profile as an input parameter that would produce a positive gradient of through-focus retinal image quality in the direction of eye growth, as indicated in Table 2 and optimising the power profile (front surface of correcting contact lens) to achieve a required positive gradient. The lens design is described as the axial power variation in diopters across the optic zone diameter. The example provided may have application to a non-progressing hyperope whose spherical refractive error is +2.00 D and this information is indicated by a dual gray line on the power profile.

As explained above, the example power profiles shown in FIGS. 17 to 26 were selected based on the slope of RIQ around the retina. Across these examples, substantial variations in the value of RIQ can occur. These variations occur on-axis, across the pupil diameter, and at different field angles. Additional selection criteria are the value of RIQ and the change in RIQ with field angle. In particular the selection may be made to maximise one or more of RIQ on-axis, across the pupil diameter (with or without reduction in light of the Stiles-Crawford effect) and at different field angles. In addition, the size of the pupil of the recipient may also be used as a selection criterion—e.g. a first aberration profile may better suit a first recipient with a normal pupil size of 4 mm and a second aberration profile may better suit a second recipient with a normal pupil size of 5 mm. The ‘normal’ pupil size may optionally be selected having regard to lifestyle factors, such as the amount of time a person spends indoors versus outdoors. Additional examples referred to below incorporate these selection criteria. First however, to provide a point of comparison, the RIQ performance of a single vision lens is described and shown in FIG. 27.

FIG. 27 shows a graph of a measure of a through focus RIQ metric, which in this case, and in each of the following examples, is Visual Strehl Ratio (monochromatic). The RIQ may result, for example, from a single vision contact lens with a power of −2.00 D used to correct a recipient model myopic eye with −2.00 D only. The horizontal (independent) axis shows the through focus, in Diopters. The zero (‘0’) value on the horizontal axis represents the location of the focal point of the single vision lens and the vertical (dependent) axis shows the RIQ. Three plots are provided, one for on-axis (circles), one for a field angle of 10 degrees (triangles) and one for a field angle of 20 degrees (crosses). Herein, the term ‘global’ is used to refer to consideration across a range of field angles, including zero. Thus, the graph shows ‘Global through focus RIQ’, as it includes plots across a range of field angles. While a single vision lens has symmetrical RIQ on-axis at zero field angle, it has asymmetrical through focus RIQ at non-zero field angles, including both at 10 and 20 degrees. In particular, the graph shows that RIQ improves in the direction of eye growth at non-zero field angles. Under the optical feedback mechanism explanation of emmetropisation, such as those described in U.S. Pat. Nos. 7,025,460 and 7,503,655 (Smith et al), peripheral as well as on-axis vision provides a stimulus for eye growth.

FIG. 28 shows a graph of RIQ for an embodiment of a lens (named ‘Iteration A1’) selected to address the optical feedback mechanism explanation of emmetropisation where eye growth is to be discouraged (e.g. to address progressing myopia or to address a risk of developing myopia). The data for FIG. 28 was prepared for a pupil size of 4 mm and to address the same level of myopia as for the Single Vision Iteration. Comparing FIG. 28 with FIG. 27, the RIQ no longer improves in a direction of eye growth for non-zero field angles. In particular, the RIQ has a strong trend towards degrading in the direction of eye growth for 10 degrees off-axis. While there may be a slight improvement or no substantially no change in RIQ about the retina at 20 degrees off-axis, the overall effect is strongly biased towards degrading RIQ in the direction of eye growth. FIG. 29 shows a power profile that results in the RIQ graph of FIG. 28.

FIG. 30 shows a graph of RIQ for another embodiment of a lens (Iteration A2) selected to address the optical feedback mechanism explanation of emmetropisation. The data for FIG. 30 was prepared for a pupil size of 5 mm.

FIGS. 31 and 32 show graphs of the RIQ for two other embodiment of a lens (Iteration C1 and Iteration C2 respectively) selected to address the optical feedback mechanism explanation of emmetropisation, but in this case to provide improving RIQ in the direction of eye growth (e.g. to provide a stimulus to an eye to grow to correct hyperopia). FIGS. 31 and 32 show exemplary embodiments selected with different weights to the selection criteria. In the power profile that gives FIG. 31, achieving a high on-axis RIQ was given more weight than achieving a high RIQ across a large range of field angles. In the power profile that gives FIG. 32, more weight was given to providing a high RIQ across a large range of field angles than to achieving a high RIQ on-axis.

Table 3 lists the defocus and higher order aberrations coefficients up to 20th order, in microns, over a 5 mm pupil diameter for the above described power profiles.

TABLE 3 Defocus and higher order Spherical aberration coefficients over a 5 mm pupil for a single vision lens and four exemplary embodiments that provide a required slope for through focus RIQ. Iteration C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Single Vision −1.800 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Lens Iteration A1 −1.568 0.107 −0.017 −0.016 −0.022 −0.008 0.026 0.005 −0.016 0.003 Iteration A2 −1.562 0.115 −0.011 −0.011 −0.019 −0.007 0.025 0.004 −0.017 0.005 Iteration C1 1.468 −0.135 0.020 0.029 0.036 0.011 −0.036 −0.008 0.022 −0.003 Iteration C2 1.468 −0.116 0.035 0.010 −0.013 −0.030 −0.014 0.025 0.004 −0.016

9. Application to Presbyopia

Extending the through focus RIQ may provide particular benefit in the context of presbyopia. The reduced ability of the eye to accommodate may be partially compensated/mitigated by using the extended through focus approach described herein.

In some embodiments the through focus RIQ is extended further by taking a monocular approach. In particular, one eye may have aberrations optimised for distance vision and the other eye optimised for near vision. This optimisation is achieved by selecting different base powers (i.e. effective refractive prescriptions) for the lenses. The extended through focus of each lens allows the base powers to be separated further without sacrificing intermediate vision between the two base powers. Under the monocular approach, selection of an aberration profile may give a higher priority to the consideration of the RIQ and through focus RIQ, and change in RIQ and through focus RIQ at different pupil sizes (which reflect the change in the eye with different accommodation).

Similarly, a lens or optical device may be designed as a bifocal or multifocal lens, with one or both of the parts incorporating aberration profiles as described herein to extend through focus RIQ. A combination of bifocal/mutlifocal lenses or devices and the monocular approach can increase the range of vision. For example, with reference to bifocal lenses one eye may have far distance vision in the upper quadrants and near vision in the lower quadrants and the other eye may have intermediate vision in the upper quadrants and near vision in the lower quadrants. The two lower quadrants may optionally have different base powers, for example set at 2.00 D and 1.00 D.

When different lenses or different parts of lenses are used together, the base powers may be selected so that the through focus RIQ overlaps. For example, the base powers may be selected so that in combination the Visual Strehl Ratio does not drop below 0.10, 0.20, 0.30, 0.40 or another selected value, between the combined RIQ profiles.

A) Examples for Presbyopia

FIG. 33 shows a graph of through focus RIQ (in this case Visual Strehl Ratio) for seven power profiles. In this figure the vertical axis (RIQ) is defined on a logarithmic scale. FIG. 33 was obtained for a 5 mm pupil size and an eye with no myopia or hyperopia and no other higher order aberrations. Each power profile can be adapted to a myopic or hyperopic eye by incorporating an appropriate correcting defocus term, which does not affect the higher order aberrations defining the power profiles used for form FIG. 33.

The seven power profiles are: a power profile that may appear in a conventional centre-distance aspheric multifocal lens (indicated by triangles in FIG. 33); a power profile that may appear in a conventional centre-near multifocal lens (indicated by ‘x’ in FIG. 33); a power profile that may appear in a centre-distance concentric bifocal lens (indicated by filled ‘□’ in FIG. 33); a power profile that may appear in a centre-near concentric bifocal lens (indicated by empty ‘⋄’ in FIG. 33) and three iterations (Iteration B1, Iteration B2, Iteration B3) including a favourable combination of spherical aberration (indicated by filled circles, bold ‘+’ signs and a concentric circle pairs, respectively, in FIG. 33).

The power profiles for each of these are shown in FIGS. 34 to 40. The centre-distance and centre-near aspheric multifocals had the centre component extend to about 2 mm and the outer zone power commence at a radius of about 1.8 mm. A linear transition was provided between the near and distance power zones. The concentric bifocals both had a ring structure, alternating between an additional power of 2 Diopters and no addition power.

Table 4 lists the defocus and higher order spherical aberration coefficients up to 20^(th) order, in microns, over a 5 mm pupil diameter, for the three exemplary embodiment power profiles, namely: Iteration B1(FIG. 38), Iteration B2 (FIG. 39) and Iteration B3 (FIG. 40), respectively.

TABLE 4 Defocus and Spherical aberration coefficients of three exemplary embodiments for presbyopia Iteration C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Iteration B1 −0.096 −0.135 0.020 0.029 0.036 0.012 −0.036 −0.010 0.022 0.000 Iteration B2 −0.092 0.032 0.074 −0.015 −0.006 −0.018 −0.009 0.007 0.011 0.002 Iteration B3 0.033 0.003 0.077 −0.045 −0.023 0.010 0.014 0.007 0.003 −0.014

Table 5 lists out the defocus and higher order spherical aberration coefficients up to 20^(th) order, in microns, over a 5 mm pupil diameter, for the described power profiles, namely, centre-distance aspheric multifocal (FIG. 34), and centre-near aspheric multifocal (FIG. 35), respectively.

TABLE 5 Defocus and Higher order spherical aberration coefficients of both centre- distance and centre-near type aspheric multifocal lenses Iteration C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Centre-Distance 1.150 0.181 0.090 0.020 0.000 0.000 0.000 0.000 0.000 0.000 bifocal Centre-Near 0.324 −0.244 0.114 −0.021 −0.013 0.011 0.000 0.000 0.000 0.000 bifocal

In the aspheric multifocal lenses the spherical aberration coefficients progressively decrease in absolute magnitude with an increase in order. This is in contrast to the power profiles of Iteration B1, Iteration B2 and Iteration B3, which include at least one higher order spherical aberration term with an absolute value coefficient greater than the absolute value of the coefficient for a lower order term. This characteristic is present in many embodiments of power profile described herein.

From FIG. 33, it can be noted that the centre-distance aspheric multifocal has a RIQ of 0.23 for distance vision, which substantially inferior than the other power profiles. However, performance of this lens as gauged by the RIQ metric is maintained relatively constant over a large through focus range. For example, at −0.4 Diopters the RIQ is about 0.2, at 0.67 the RIQ is about 0.18 and at −1.0 Diopters, the RIQ is about 0.12.

The centre-near aspheric multifocal has a RIQ for distance vision, of about 0.50. The centre-near bifocal falls to an RIQ of about 0.24 at −0.67 Diopters (still better than the centre-distance aspheric multifocal). However, beyond that the centre-near aspheric multifocal has a rapidly decreasing RIQ and at −1.0 Diopters has an RIQ of about 0.08.

Both of the concentric bifocals (centre-distance and -near) have a low RIQ of 0.13 and 0.21 for distance vision. Both of the concentric bifocals maintain their level of RIQ or better over a range of approximately 1.1 Diopters.

Iteration B1, Iteration B2 and Iteration B3 all have at least as good RIQ at distance vision as the centre near bifocal and better RIQ as the eye accommodates. For example Iteration B2 has an RIQ of about 0.53 at −0.40 Diopters, about 0.32 at −0.67 Diopters and about 0.13 at −1.0 Diopters. However, the through focus performance of each of Iteration B1, Iteration B2 and Iteration B3 can be further extended. This extension is achieved by shifting the curves to the left in FIG. 33. However, the performance of the centre-near aspheric multifocal lens cannot be shifted in this manner without substantially affecting performance, due to the asymmetric RIQ that decreases substantially more rapidly for plus powers (right hand side of FIG. 33).

For example, all three of these iterations have an RIQ of about 0.40 at +0.55 D. Combining the spherical aberration terms with a +0.55 D defocus term will shift the RIQ value for distance vision to the value for +0.55 D in FIG. 33. Taking again Iteration B2, the through focus performance is modified as follows: an RIQ of about 0.40 at distance vision, an RIQ of about 0.53 at −0.40 Diopters, about 0.64 at −0.67 Diopters, about 0.52 at −1.0 Diopters, about 0.40 at −1.1 Diopters, and about 0.15 at −1.5 Diopters.

Accordingly, by shifting the distance vision point in a lens with combinations of HOA that extend through focus RIQ performance, then the lenses, devices and methods that provide the combination of HOA can have a substantially improved through focus performance. This is achieved while maintaining at least as good RIQ as a centre near aspheric multifocal and substantially improved RIQ in comparison to a centre distance aspheric multifocal. The amount of defocus plus power added to shift the RIQ curves is a matter of choice, representing a trade-off between distance vision RIQ and near vision RIQ.

Table 6 shows the defocus (leftmost column) and RIQ values for each of the power profiles described above. It also shows the defocus values shifted by +0.55 D, applicable when to Iteration B1, Iteration B2 and/or Iteration B3 are modified by this amount.

TABLE 6 RIQ values for two bifocal lenses, two concentric bifocal lenses and three aberration profiles for extended through focus RIQ Centre- Centre- Centre- Centre- Distance Near Distance Near Defocus Defocus aspheric aspheric Iteration Iteration Iteration concentric concentric shifted (D) multifocal multifocal B1 B2 B3 bifocal bifocal by +0.50 −1.1085 0.1021 0.0601 0.1342 0.0918 0.0971 0.2025 0.1349 −0.6085 −0.9977 0.1212 0.0768 0.1831 0.1338 0.1228 0.2447 0.1524 −0.4977 −0.8868 0.1407 0.1062 0.2394 0.1882 0.1577 0.2913 0.1675 −0.3868 −0.7760 0.1598 0.1574 0.2957 0.2511 0.2095 0.3362 0.1789 −0.2760 −0.6651 0.1776 0.2383 0.3423 0.3160 0.2830 0.3700 0.1851 −0.1651 −0.5543 0.1931 0.3481 0.3867 0.4262 0.3723 0.3839 0.1855 −0.0543 −0.4434 0.2060 0.4699 0.4550 0.5318 0.4583 0.3735 0.1805 0.0566 −0.3326 0.2162 0.5715 0.4992 0.6099 0.5266 0.3417 0.1709 0.1674 −0.2217 0.2237 0.6185 0.5110 0.6451 0.5691 0.2969 0.1584 0.2783 −0.1109 0.2284 0.5913 0.4924 0.6369 0.5879 0.2495 0.1444 0.3891 0.0000 0.2304 0.4980 0.5014 0.5993 0.5906 0.2076 0.1300 0.5000 0.1109 0.2294 0.3702 0.4924 0.5511 0.5825 0.1754 0.1167 0.6109 0.2217 0.2249 0.2468 0.5110 0.5055 0.5609 0.1539 0.1055 0.7217 0.3326 0.2160 0.1549 0.4992 0.4648 0.5182 0.1418 0.0973 0.8326 0.4434 0.2048 0.1010 0.4550 0.4232 0.4513 0.1367 0.0924 0.9434 0.5543 0.2000 0.0758 0.3867 0.3741 0.3672 0.1358 0.0908 1.0543 0.6651 0.2173 0.0650 0.3082 0.3154 0.2815 0.1363 0.0917 1.1651 0.7760 0.2727 0.0588 0.2327 0.2511 0.2095 0.1362 0.0940 1.2760 0.8868 0.3701 0.0535 0.1694 0.1882 0.1577 0.1347 0.0962 1.3868 0.9977 0.4907 0.0491 0.1219 0.1338 0.1228 0.1325 0.0992 1.4977 1.1085 0.5962 0.0458 0.0896 0.0918 0.0971 0.1305 0.1087 1.6085

B) Effect of Pupil Size

FIGS. 41 to 43 show the variation in through focus RIQ with pupil size for Iteration B1, Iteration B2 and Iteration B3 respectively. Each power profile is relatively stable, in that the RIQ retains the combination of a relatively high RIQ (in comparison to, for example, a centre distance aspheric multifocal) in combination with a relatively long through focus range (in comparison to, for example, a centre near aspheric multifocal). FIGS. 44 and 45 show the variation in through focus RIQ with pupil size for the two concentric bifocals and two aspheric multifocals, respectively. From these figures it can be seen that, comparatively, the change in RIQ and through focus RIQ performance is less stable for these lenses than Iteration B1, Iteration B2 and Iteration B3.

C) Monocular Design

As described above, Iteration B2 can provide an RIQ of 0.40 or above from distance vision to about an intermediate vergence of about 1.1 Diopters. When appropriate level of defocus is added to the same iteration while correcting the other eye, through-focus RIQ can be extended from 1.1 Diopters to up close, say 2.20 D target vergence, i.e. binocularly combined the candidate eye may maintain an RIQ of 0.40 or above from distance test distance to all the way up close to 2.2 Diopters. Using this monocular design approach and assuming the recipient accepts the monocular design, the combined through focus performance is substantially extended.

Referring to the through focus profiles shown in FIGS. 46 and 47, which are described herein below, under the monocular design approach, one lens will be selected to have a base power that shifts the through focus curve to the extreme left (starting at −2.50 D mark) and the other lens selected to have a base power that shifts the through focus curve slightly to the left (starting at −1.50 D mark).

FIGS. 46 and 47 show the through-focus RIQ of the design of two pairs of power profiles (Binocular ‘Q’ correction). Each lens in the pair has been designed to extend RIQ in combination with the other lens in the pair. The defocus and higher order spherical aberration coefficients for these combinations are specified in Tables 7 and 8 respectively.

TABLE 7 Defocus and higher order spherical aberration coefficients of first exemplary embodiment for monocular design of lenses for presbyopia (Effective add of 1.50D in the negative direction of through-focus curve) Combination C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Right Eye 0.28 −0.100 0.025 0.075 0.025 0.025 0.025 0.025 0.025 0.000 Left Eye 0.57 0.125 −0.075 −0.075 −0.025 0.000 0.025 0.025 −0.025 −0.025

TABLE 8 Defocus and higher order spherical aberration coefficients of second exemplary embodiment for monocular design of lenses for presbyopia (Effective add of 2.50D in the negative direction of through-focus curve) Combination C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Right Eye 0.433 −0.100 −0.050 0.025 0.025 −0.025 −0.025 0.000 0.000 0.000 Left Eye 0.866 −0.100 −0.050 0.025 0.025 −0.025 −0.025 0.000 0.000 0.000

The power profiles described in relation to Table 7 and Table 8 are examples of combinations of higher order aberrations that provide enhanced through-focus performance on the negative side of the through-focus function. Similarly, using this monocular design approach, the combined through-focus performance can also be substantially extended on the right side of the through-focus function, provided an appropriate level of defocus is added to a selected combination of higher order aberrations. FIGS. 48 and 49 show examples with a relatively constant RIQ (>0.35) over a range of defocus, in the positive direction of the through-focus function. The defocus and higher order spherical aberration coefficients for these combinations are specified in Tables 9 and 10, respectively.

TABLE 9 Defocus and higher order spherical aberration coefficients of third exemplary embodiment for monocular design of lenses for presbyopia (Effective add of 1.50D in the positive direction of through-focus curve) Combination C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Right Eye −0.28 −0.125 −0.050 0.075 0.025 −0.025 0.000 0.000 0.000 0.000 Left Eye −0.43 −0.125 −0.050 0.075 0.025 −0.025 0.000 0.000 0.000 0.000

TABLE 10 Defocus and higher order spherical aberration coefficients of fourth exemplary embodiment for monocular design of lenses for presbyopia (Effective add of 2.50D in the positive direction of through-focus curve) Combination C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Right Eye −0.43 −0.125 −0.050 0.075 0.025 −0.025 0.000 0.000 0.000 0.000 Left Eye −0.86 −0.125 −0.050 0.075 0.025 −0.025 0.000 0.000 0.000 0.000

10. Design for Peripheral Field

In some embodiments, when selecting a combination of HOA to form a power profile, the weight given to peripheral vision may be increased. This may, for example, be applicable when the recipient plays certain sports in which peripheral vision is important.

FIG. 50 shows a graph of RIQ (again Visual Strehl Ratio), for three different power profiles that substantially equalise RIQ across the horizontal visual field. The RIQ measures were obtained for a 5 mm pupil. The defocus and higher order spherical aberration coefficients for each power profile are shown in Table 11.

TABLE 11 Defocus and higher order spherical aberration coefficients of three exemplary embodiments for substantially constant RIQ over extended horizontal field angles Iteration C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Iteration −1.506 0.111 −0.040 −0.015 0.007 0.025 0.011 −0.025 −0.003 0.017 A3 Iteration −1.504 0.114 −0.037 −0.013 0.009 0.027 0.013 −0.024 −0.002 0.016 A4 Iteration −1.501 0.117 −0.034 −0.010 0.012 0.029 0.014 −0.023 −0.002 0.015 A5

Each of Iteration A3, Iteration A4 and Iteration A5 produced an on-axis RIQ of about 0.50 across zero to 30 degrees field angle (if horizontal symmetry is assumed, that is 60 degrees in total across both nasal and temporal fields). The RIQ on-axis is also about 0.50, which is lower than some other embodiments where degradation in RIQ below 0.50 with increasing field angle is permitted.

Accordingly, in further embodiments, the RIQ on-axis may be traded-off against RIQ at high field angles. For example, RIQ may be permitted to drop to 0.20 at 30 degrees field angle (but remain at 0.50 or above for 20 degrees field angle and less), to allow a selection of HOA that increases on-axis RIQ above those shown in FIG. 50. Power profile designs for peripheral vision may be selected for a lens designed to provide a slope of RIQ (providing stimulus to retard or encourage eye growth under the optical feedback mechanism explanation for emmetropisation), or correction/lenses for presbyopia (emmetropic, myopic or hyperopic) or for other eyes.

11. Selection of Positive and Negative Phase

For any particular recipient of a lens, device or a method disclosed herein, a selection may be made between any two power profiles of opposite phases. In this context, the term ‘opposite phase’ identifies power profiles that have identical magnitudes of specific combination sets of higher order aberrations over a desired pupil, while their signs are opposite to each other. FIGS. 51 and 52 show power profile iterations E1 and E2, which are examples of power profiles with opposite phases. Table 12 reflects the magnitudes and signs of the higher order spherical aberration terms for iterations E1 and E2.

The lenses of opposite phase described herein may result in the same on-axis peak RIQ. The through focus RIQ performance of such phase profile pairs may be mirror images of each other across the Y-axis (i.e. shifted apart by defocus), as shown in FIG. 53. However, this would result only if the inherent higher order aberration profile is negligibly small (say for example primary spherical aberration in the range of −0.02 μm to 0.02 μm over a 5 mm pupil).

TABLE 12 Defocus and higher order spherical aberration coefficients of two exemplary embodiments with opposite phases (i.e. mirror imaged power profiles across the X-axis). Iteration C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) Iteration −2.015 −0.102 0.021 0.019 0.025 0.010 −0.025 −0.006 0.016 −0.003 E1 Iteration −1.573 0.102 −0.021 −0.019 −0.025 −0.010 0.025 0.006 −0.016 0.003 E2

The interactions between the inherent aberration profiles of the candidate eyes and a selected phase profile may either have a) an improved or b) degraded effect on the objective/subjective optical/visual performance. As the through-focus RIQ is dependent on the inherent aberration profile, a phase profiles selected for instance may be useful to change the slope of through-focus RIQ in the direction that would favour the emmetropisation process for myopic or hyperopic eyes; or alternatively the same phase profile could be used to mitigate the presbyopic symptoms in alternative candidate eyes.

FIGS. 54 and 55 show how the through-focus RIQ of opposite phase profiles are dependent on the inherent ocular aberration of the candidate eye (in this example positive spherical aberration). Accordingly, embodiments of the invention involve providing lenses of the same design, but opposite phase and allowing the recipient to select the preferred phase. The process of selection can be via an objective assessment of through-focus RIQ performance metric or could be purely a subjective preference via visually guided tests.

12. Combination Identification and Selection

As described above, it is possible to provide a desirable on-axis RIQ for distance and appropriate through focus RIQ that would enable better visual performance for intermediate and near vergences by choosing an appropriate combination of HOA. This combination of higher order aberrations may contain a correction for the inherent aberration profile of the test candidate. The Appendix A to this specification lists 78 combinations of higher order spherical aberration coefficients that provide both a usefully high RIQ and an option to provide an extended through focus RIQ in the negative direction (left hand side). Also shown in the Appendix A, as a point of comparison, is a combination which does not have any spherical aberration, of any order. The Appendix B shows the through-focus RIQ values for the combinations listed in the Appendix A. All calculations were performed for a pupil size of 4 mm, however the approach can be extended to any other appropriate/desired pupil sizes if required.

The through-focus RIQ measures of the 78 aberration combinations are shown in FIG. 56, the black line showing the symmetrical RIQ that has resulted from a combination that has no higher order aberrations and while the lighter lines (i.e. gray lines) showing the enhanced performance in the negative direction of the through-focus RIQ function, for the 78 combinations that involve higher order spherical aberration terms.

From FIG. 56, a number of observations can be made. All of the 78 profiles with higher order spherical aberration terms provide an extended through focus performance in the negative direction, particularly when an appropriate selection of a negative power is made to shift the plotted through-focus profile towards negative defocus (left). All of the 78 profiles include a range over which RIQ is 0.10 or higher of at least 2 Diopters. Several of the 78 profiles include a range over which RIQ is 0.10 or higher of at least 2.25 Diopters. All of the 78 profiles include an RIQ (Visual Strehl Ratio—monochromatic) that peaks above 0.35. Many of the profiles include an RIQ that peaks above the thresholds of 0.40, 0.50, 0.60 and 0.70 and some combinations result in a peak that lies above 0.80 mark.

The spherical aberration terms vary in the combinations, from one (example: combination 77) through to all nine. In other embodiments even higher orders of spherical aberration terms may be added, to create additional combinations.

The combination 77 in the appendix A introduces only primary spherical aberration. Primary spherical aberration was proposed in the U.S. Pat. No. 6,045,578 (Collins and Wildsoet) for progressing myopia. The combination 77 shows that by selecting a particular level of primary spherical aberration, the aberration profile may be beneficially used for a presbyopic eye. In addition, considering the application of myopia, when combination 77 (or any other embodiment including only PSA) is set with a focal length matching the existing myopia, then the on-axis through focus RIQ is substantially neutral, in that the peak RIQ is placed on the retina. Placing the peak RIQ on the retina would accord with a traditional design approach as taught by Collins. In contrast, a stimulus to retard eye growth on-axis under the optical feedback explanation of emmetropisation is achieved if the retina is located on the negative side of the graph shown in FIG. 57 (i.e. the focal length of the lens is longer than the eye). In other words, the aberration profile will include a C(2,0) term with further negative power over the amount required to correct myopia.

Appendix C to this specification lists another 67 combinations of higher order coefficients that provide both a usefully high RIQ and an option to provide an extended through-focus RIQ in the positive direction (right hand side). Also shown in Appendix C, as a point of comparison, is a combination which does not have any spherical aberration of any order. The Appendix D shows the through-focus RIQ values for the combinations listed in Appendix C. Again, all calculations were performed for a pupil size of 4 mm, however the approach can be extended to any other appropriate/desired pupil sizes, if required.

The through-focus RIQ measures of the 67 aberration combinations are shown in the FIG. 58, the black line showing the symmetrical RIQ that has resulted from a combination that has no higher order aberrations and while the lighter (i.e. gray lines) showing the enhanced performance in the positive direction of the through-focus RIQ function, for the 67 combinations that involved higher order spherical aberration terms.

From the FIG. 58, a number of observations can be made. All of the 67 profiles with higher order spherical aberration terms provide an extended through-focus performance in the positive direction particularly when appropriate selection of a negative power is made to shift the plotted through-focus profile towards negative defocus (left). All of the 67 profiles include a range over which the RIQ is 0.10 or higher of greater than 2.50 D.

FIG. 59 shows an example workflow diagram for identifying a power profile for application to a presbyopic eye.

13. Spherical Aberration and Astigmatism

In the previous sections iterations B1, B2 and B3 were described for emmetropic presbyopia. When considering the astigmatic presbyopia, two different methods can be adopted. A first method of correction is completed by considering astigmatic refractive error as an equivalent sphere. In this method, the spherical equivalent prescription is deduced by dividing the cylindrical/astigmatic power divided two (S=−C/2). This is a very common approach often considered to address low to moderate amounts of astigmatism, say up to −1.50 D. Once the equivalent sphere is availed, the same iterations described herein, say for example B1, B2 or B3 can be used as an effective prescription, once the defocus term is adjusted to suit the spherical equivalent.

A second method considers preparation of a toric prescription for both astigmatism and presbyopia. FIG. 60 shows an exemplary embodiment that includes a toric power profile to treat both astigmatism and presbyopia. In this case, the prescription is made to correct an individual who has an astigmatic correction of −1.00 D @ 90 and requires an additional power to enable near viewing. As can be noted from the figure, the difference between the horizontal and vertical meridian is −1.00 D, this magnitude is set to corrects the astigmatism in the above test case; while the higher order spherical aberration combination is aimed to mitigate the presbyopic symptoms.

14. Implementation

Aberration profiles of the types described herein above may be implemented in a number of lenses, ocular devices and as methods.

For example, contact lenses (hard or soft), corneal onlays, corneal inlays, and lenses for intraocular devices (both anterior and posterior chamber) may all include the combination aberration profiles discussed. Techniques to design lenses and to achieve a power profile are known and will are not described herein in any detail.

The aberration profiles can be applied to spectacle lenses. However, because the aberration profiles require alignment of the eye with the centre of the optics providing the aberration profile, then benefit may only be apparent for one particular direction of gaze. Recently electro-active lenses have been proposed that can track the direction of gaze and change the refractive properties of the lenses in response. Using electro-active lenses the aberration profile can move with the eye, which may increase the utility of the disclosed aberration profiles for spectacle lenses.

The aberration profile may be provided on a lens of an intraocular lens. In some embodiments the intraocular lens may include haptics that provide for accommodation. In other embodiments the lens may have a fixed focal length. The aberration profile may be provided on a supplementary endo-capsular lens.

The disclosed aberration profiles may be provided to an eye through computer-assisted surgery. For example refractive surgery or corneal ablation may be used to form a selected aberration profile. The power profile or required change in corneal shape is determined and input to the laser system (LASIK or LASEK) for application to the eye of the patient.

Where the aberration profiles are to be included in a lens, then the aberration profile may first be translated into a lens thickness profile for input to computer assisted manufacturing. Taking for example, the lens power profile D1 shown in FIG. 61, which is a combination of Zernike higher order spherical aberration terms, is converted to an axial thickness profile for a contact lens, taking account of the refractive index of the contact lens material material (in this case, contact lens material refractive index of 1.420). An example thickness profile is shown in FIG. 62. Features of the power/thickness profiles can either be put on the front or the back surface or a combination of both, under consideration of the refractive indices of lens and cornea. Once all the parameters i.e. the thickness profile, power profile, back surface shape, diameter and refractive index of the material have been determined, then this is input to a computer assisted lathe to produce the contact lens. Similar approaches can be adopted for other lenses.

The aberration profile may be selected and identified as a custom lens for an individual. The process for design of the aberration profile includes measuring the wavefront aberration of the eye and designing an aberration profile to achieve a through focus RIQ profile described herein. The design process includes identifying the spherical aberration in the natural eye only and designing an aberration profile for the lens, device or method that, in combination with the spherical aberration of the eye provides a required RIQ profile. As described herein above, the required RIQ profile may differ depending on the application of the lens—as different requirements may apply between a person with progressing myopia and a person with presbyopia. In some embodiments other aberrations in the eye, for example astigmatism, coma or trefoil are ignored. In other embodiments, these are taken into account. For example, as described above, the presence of astigmatism affects the combinations of aberrations that provide a through focus RIQ that inhibits eye growth under the optical feedback explanation of emmetropisation. In other embodiments these aberrations are incorporated into the design. For example, when producing a lens design, a base lens may be produced that corrects for any defocus and corrects one or more of astigmatism, coma and trefoil. On top of this base profile is provided a spherical aberration profile designed to achieve (in the sense of using as an objective design) the profiles described herein. The spherical aberration profile may be selected using a trial and error approach, for example by identifying a candidate profile, computing the through focus RIQ and evaluating whether the through focus RIQ has an acceptable profile.

In another approach aberration profiles may be designed for population averages. One approach for designing population average lenses is to normalise the design for pupil size.

The description of the aberration profiles for lenses, devices and methods has been provided by way of mathematical explanation. This allows for precision in describing the aberration profiles. However, lenses, devices and methods will not have such precision. For example tolerances and inaccuracies arising during manufacture will result in variations of the lens profile. The approximate power profile of a lens can be measured using a wavefront aberrometer. From this an approximate measure of through focus RIQ, for example Visual Strehl Ratio, can be determined.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

15. Appendix A Example Combinations of Spherical Aberration

Combination C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) No Aberr 0 0 0 0 0 0 0 0 0 0  1 0 −0.125 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000  2 0 −0.100 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000  3 0 −0.100 −0.025 0.025 0.000 0.000 0.000 0.000 0.000 0.000  4 0 −0.100 0.025 0.075 0.025 0.025 0.025 0.025 0.025 0.000  5 0 −0.075 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000  6 0 −0.075 −0.025 0.050 0.000 −0.025 −0.025 0.000 0.025 0.000  7 0 −0.050 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000  8 0 −0.050 −0.050 0.050 0.025 0.000 0.000 0.000 0.000 0.000  9 0 −0.050 −0.025 0.050 0.000 −0.025 −0.025 0.000 0.025 0.025 10 0 −0.025 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 11 0 −0.025 −0.025 0.050 0.025 −0.025 −0.025 0.000 0.025 0.025 12 0 0.000 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 13 0 0.000 −0.075 0.050 0.025 0.000 0.025 0.000 −0.025 0.000 14 0 0.000 −0.050 0.000 −0.025 −0.025 0.025 0.025 −0.025 −0.025 15 0 0.000 −0.050 0.050 0.025 −0.025 −0.025 −0.025 0.000 0.025 16 0 0.000 −0.025 0.075 0.000 −0.025 0.025 0.025 0.025 0.025 17 0 0.025 −0.075 0.000 −0.025 −0.025 0.025 0.025 0.000 0.000 18 0 0.025 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 19 0 0.025 −0.075 0.025 0.025 −0.025 −0.025 −0.025 0.000 0.025 20 0 0.025 −0.075 0.050 0.025 −0.025 −0.025 −0.025 0.000 0.000 21 0 0.025 −0.050 0.000 0.000 0.000 0.000 0.000 0.000 0.000 22 0 0.025 −0.050 0.050 0.000 −0.025 −0.025 0.000 0.025 0.025 23 0 0.025 −0.050 0.050 0.025 0.000 0.000 −0.025 −0.025 0.000 24 0 0.025 −0.025 0.075 0.000 −0.025 0.025 0.025 0.025 0.025 25 0 0.050 −0.075 0.000 0.000 −0.025 0.000 0.000 0.025 0.025 26 0 0.050 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 27 0 0.050 −0.075 0.025 0.025 −0.025 0.000 0.000 −0.025 0.000 28 0 0.050 −0.075 0.025 0.025 −0.025 0.000 0.000 0.025 0.025 29 0 0.050 −0.075 0.025 0.025 0.000 0.000 −0.025 −0.025 0.000 30 0 0.050 −0.075 0.025 0.025 0.000 0.025 0.025 0.025 0.025 31 0 0.050 −0.050 0.000 0.000 0.000 0.000 0.000 0.000 0.000 32 0 0.050 −0.025 −0.025 −0.025 −0.025 0.025 0.025 0.000 −0.025 33 0 0.050 −0.025 0.075 0.025 −0.025 0.025 0.025 0.025 0.025 34 0 0.075 0.050 −0.025 −0.025 0.000 0.000 0.000 0.000 0.000 35 0 0.075 −0.075 −0.025 −0.025 0.000 0.025 0.000 0.000 0.000 36 0 0.075 −0.075 −0.025 0.000 0.000 0.025 0.025 0.000 0.000 37 0 0.075 −0.075 0.000 0.000 −0.025 −0.025 0.000 0.000 0.000 38 0 0.075 −0.075 0.000 0.000 −0.025 0.000 0.000 0.000 0.000 39 0 0.075 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 40 0 0.075 −0.075 0.000 0.025 −0.025 −0.025 0.000 0.000 0.000 41 0 0.075 −0.075 0.000 0.025 −0.025 0.000 0.000 0.000 0.000 42 0 0.075 −0.050 −0.050 −0.025 0.000 0.000 0.025 0.000 −0.025 43 0 0.075 −0.050 0.000 0.000 0.000 0.000 0.000 0.000 0.000 44 0 0.075 −0.025 0.000 0.000 0.000 0.000 0.000 0.000 0.000 45 0 0.075 −0.025 0.050 0.000 −0.025 0.025 0.025 0.000 0.000 46 0 0.100 −0.075 −0.050 −0.025 0.000 0.025 0.025 −0.025 −0.025 47 0 0.100 −0.075 −0.050 0.000 0.000 0.025 0.025 −0.025 −0.025 48 0 0.100 −0.075 −0.025 0.000 0.000 0.000 0.000 0.000 0.000 49 0 0.100 −0.075 −0.025 0.000 0.000 0.025 0.000 0.000 0.000 50 0 0.100 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 51 0 0.100 −0.075 0.000 0.025 −0.025 −0.025 0.025 0.025 0.000 52 0 0.100 −0.050 −0.050 −0.025 0.000 −0.025 −0.025 −0.025 −0.025 53 0 0.100 −0.050 −0.025 −0.025 −0.025 0.025 0.000 −0.025 0.000 54 0 0.100 −0.050 0.000 0.000 0.000 0.000 0.000 0.000 0.000 55 0 0.100 −0.050 0.000 0.000 0.000 0.025 0.025 0.000 0.000 56 0 0.100 −0.050 0.000 0.000 0.000 0.025 0.025 0.025 0.025 57 0 0.100 −0.050 0.000 0.025 0.025 0.000 −0.025 −0.025 −0.025 58 0 0.100 −0.025 0.000 0.000 0.000 0.000 0.000 0.000 0.000 59 0 0.100 −0.025 0.000 0.025 0.025 0.000 −0.025 −0.025 −0.025 60 0 0.100 −0.025 0.025 −0.025 −0.025 0.025 0.025 0.000 0.000 61 0 0.100 0.000 0.000 −0.025 0.000 0.025 0.000 0.000 0.025 62 0 0.100 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 63 0 0.100 0.000 0.050 0.000 −0.025 0.025 0.000 −0.025 0.000 64 0 0.125 −0.075 −0.075 −0.025 0.000 0.025 0.025 −0.025 −0.025 65 0 0.125 −0.075 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 66 0 0.125 −0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 67 0 0.125 −0.050 −0.025 −0.025 −0.025 0.000 0.000 0.000 0.000 68 0 0.125 −0.050 −0.025 −0.025 −0.025 0.025 0.000 0.000 0.000 69 0 0.125 −0.050 −0.025 0.000 0.000 0.025 0.025 0.000 0.000 70 0 0.125 −0.050 0.000 0.000 0.000 0.000 0.000 0.000 0.000 71 0 0.125 −0.050 0.000 0.025 0.025 0.025 0.000 0.000 0.000 72 0 0.125 −0.025 0.000 −0.025 −0.025 0.000 0.000 −0.025 −0.025 73 0 0.125 −0.025 0.000 0.000 0.000 0.000 0.000 0.000 0.000 74 0 0.125 −0.025 0.025 0.000 −0.025 0.000 0.000 0.000 0.000 75 0 0.125 −0.025 0.025 0.000 0.000 0.025 0.025 0.000 0.000 76 0 0.125 −0.025 0.025 0.025 0.025 −0.025 0.025 0.025 0.025 77 0 0.125 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 78 0 0.125 0.000 0.025 −0.025 −0.025 0.025 0.000 −0.025 −0.025

16. Appendix B Through Focus RIQ for Combinations of Spherical Aberration in Appendix A

Combination −1.50 −1.25 −1.00 −0.75 −0.50 −0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 No Aberr 0.024 0.040 0.073 0.148 0.307 0.709 1.000 0.709 0.307 0.148 0.073 0.040 0.024  1 0.089 0.135 0.192 0.243 0.304 0.434 0.606 0.667 0.542 0.329 0.152 0.056 0.021  2 0.084 0.131 0.196 0.265 0.346 0.482 0.643 0.676 0.514 0.281 0.113 0.036 0.012  3 0.028 0.053 0.115 0.258 0.473 0.628 0.648 0.595 0.479 0.310 0.161 0.071 0.028  4 0.039 0.067 0.153 0.313 0.458 0.493 0.477 0.492 0.470 0.361 0.220 0.112 0.052  5 0.082 0.128 0.198 0.281 0.384 0.532 0.675 0.675 0.481 0.236 0.080 0.021 0.006  6 0.100 0.129 0.157 0.246 0.402 0.514 0.542 0.559 0.515 0.338 0.146 0.051 0.024  7 0.083 0.129 0.199 0.289 0.412 0.576 0.704 0.666 0.445 0.196 0.054 0.010 0.002  8 0.069 0.105 0.176 0.305 0.479 0.603 0.614 0.565 0.454 0.262 0.099 0.030 0.010  9 0.124 0.168 0.181 0.212 0.338 0.502 0.579 0.579 0.508 0.319 0.117 0.027 0.016 10 0.089 0.133 0.201 0.293 0.425 0.607 0.730 0.656 0.409 0.161 0.034 0.003 0.001 11 0.104 0.159 0.199 0.247 0.359 0.508 0.581 0.570 0.502 0.326 0.125 0.035 0.023 12 0.098 0.141 0.206 0.293 0.423 0.618 0.749 0.649 0.377 0.134 0.021 0.001 0.002 13 0.157 0.206 0.250 0.282 0.354 0.482 0.542 0.480 0.364 0.232 0.120 0.060 0.032 14 0.092 0.184 0.314 0.371 0.390 0.505 0.592 0.481 0.297 0.204 0.161 0.097 0.041 15 0.153 0.215 0.247 0.261 0.324 0.453 0.533 0.514 0.447 0.307 0.129 0.038 0.025 16 0.152 0.207 0.237 0.260 0.363 0.509 0.531 0.442 0.363 0.265 0.137 0.056 0.029 17 0.158 0.218 0.286 0.308 0.324 0.457 0.611 0.564 0.352 0.181 0.101 0.048 0.011 18 0.111 0.152 0.213 0.293 0.410 0.604 0.754 0.650 0.356 0.113 0.013 0.004 0.004 19 0.168 0.205 0.235 0.285 0.367 0.476 0.539 0.482 0.365 0.253 0.138 0.052 0.023 20 0.161 0.202 0.237 0.282 0.361 0.468 0.518 0.465 0.378 0.267 0.124 0.038 0.019 21 0.081 0.116 0.174 0.255 0.405 0.680 0.878 0.715 0.342 0.093 0.015 0.002 0.001 22 0.151 0.212 0.253 0.256 0.304 0.463 0.584 0.514 0.360 0.223 0.095 0.016 0.003 23 0.153 0.205 0.242 0.255 0.316 0.493 0.638 0.563 0.363 0.201 0.096 0.041 0.023 24 0.159 0.214 0.250 0.256 0.322 0.476 0.548 0.465 0.357 0.251 0.127 0.046 0.021 25 0.158 0.201 0.231 0.253 0.312 0.472 0.648 0.612 0.359 0.141 0.075 0.067 0.043 26 0.126 0.166 0.222 0.293 0.388 0.567 0.739 0.657 0.350 0.099 0.008 0.005 0.006 27 0.161 0.203 0.236 0.253 0.304 0.475 0.648 0.593 0.370 0.190 0.091 0.039 0.015 28 0.164 0.201 0.226 0.253 0.323 0.472 0.604 0.547 0.352 0.197 0.112 0.058 0.031 29 0.171 0.206 0.240 0.274 0.328 0.463 0.608 0.564 0.362 0.193 0.094 0.036 0.012 30 0.171 0.206 0.231 0.259 0.326 0.475 0.626 0.589 0.363 0.150 0.057 0.031 0.015 31 0.097 0.135 0.192 0.268 0.389 0.628 0.848 0.728 0.347 0.078 0.006 0.001 0.003 32 0.074 0.134 0.238 0.370 0.462 0.553 0.624 0.516 0.286 0.156 0.129 0.096 0.052 33 0.159 0.212 0.245 0.251 0.305 0.461 0.564 0.496 0.375 0.264 0.138 0.048 0.019 34 0.022 0.044 0.114 0.279 0.496 0.623 0.634 0.591 0.479 0.310 0.160 0.069 0.030 35 0.161 0.200 0.244 0.318 0.404 0.493 0.584 0.550 0.352 0.162 0.072 0.032 0.009 36 0.151 0.217 0.289 0.353 0.390 0.455 0.568 0.563 0.373 0.173 0.080 0.042 0.013 37 0.151 0.206 0.264 0.304 0.336 0.450 0.630 0.628 0.372 0.127 0.038 0.014 0.004 38 0.164 0.211 0.254 0.279 0.309 0.455 0.681 0.686 0.400 0.126 0.027 0.011 0.005 39 0.142 0.181 0.232 0.292 0.364 0.512 0.699 0.664 0.364 0.097 0.005 0.006 0.008 40 0.155 0.222 0.286 0.331 0.369 0.465 0.601 0.579 0.365 0.172 0.085 0.037 0.008 41 0.151 0.204 0.251 0.282 0.320 0.459 0.661 0.659 0.405 0.163 0.062 0.031 0.018 42 0.118 0.171 0.252 0.367 0.460 0.506 0.539 0.496 0.329 0.166 0.098 0.069 0.035 43 0.115 0.156 0.212 0.283 0.376 0.563 0.784 0.729 0.371 0.080 0.001 0.003 0.005 44 0.086 0.126 0.186 0.272 0.392 0.602 0.826 0.761 0.391 0.094 0.012 0.005 0.001 45 0.153 0.203 0.257 0.284 0.316 0.452 0.609 0.566 0.367 0.207 0.104 0.035 0.011 46 0.180 0.256 0.316 0.408 0.497 0.493 0.427 0.336 0.212 0.122 0.109 0.104 0.064 47 0.171 0.253 0.325 0.407 0.458 0.443 0.429 0.400 0.289 0.173 0.131 0.112 0.066 48 0.151 0.211 0.281 0.358 0.417 0.470 0.566 0.585 0.397 0.155 0.035 0.004 0.004 49 0.155 0.203 0.255 0.330 0.407 0.472 0.560 0.561 0.375 0.168 0.075 0.042 0.018 50 0.159 0.197 0.240 0.289 0.339 0.449 0.636 0.663 0.396 0.110 0.005 0.007 0.009 51 0.185 0.272 0.360 0.392 0.353 0.357 0.461 0.486 0.330 0.168 0.108 0.077 0.037 52 0.096 0.141 0.222 0.351 0.472 0.508 0.515 0.524 0.412 0.196 0.057 0.024 0.021 53 0.158 0.206 0.242 0.306 0.392 0.462 0.534 0.533 0.381 0.208 0.116 0.063 0.025 54 0.134 0.177 0.231 0.296 0.365 0.494 0.694 0.710 0.409 0.101 0.001 0.004 0.007 55 0.152 0.204 0.259 0.316 0.366 0.464 0.626 0.630 0.369 0.110 0.031 0.028 0.016 56 0.161 0.207 0.253 0.290 0.338 0.458 0.619 0.607 0.360 0.117 0.033 0.027 0.022 57 0.143 0.197 0.268 0.357 0.426 0.471 0.522 0.486 0.298 0.128 0.086 0.078 0.044 58 0.105 0.151 0.214 0.299 0.398 0.542 0.721 0.717 0.423 0.123 0.017 0.003 0.003 59 0.110 0.169 0.259 0.371 0.457 0.518 0.571 0.515 0.302 0.113 0.068 0.073 0.053 60 0.158 0.202 0.246 0.308 0.374 0.455 0.553 0.536 0.366 0.196 0.093 0.030 0.008 61 0.118 0.160 0.205 0.284 0.407 0.520 0.588 0.569 0.421 0.224 0.088 0.026 0.007 62 0.076 0.119 0.189 0.297 0.437 0.593 0.722 0.683 0.425 0.165 0.053 0.021 0.006 63 0.156 0.207 0.243 0.258 0.318 0.460 0.563 0.511 0.364 0.236 0.140 0.075 0.044 64 0.194 0.280 0.335 0.402 0.502 0.516 0.402 0.272 0.179 0.124 0.113 0.113 0.086 65 0.155 0.251 0.353 0.432 0.463 0.418 0.355 0.368 0.387 0.303 0.163 0.062 0.021 66 0.175 0.210 0.246 0.284 0.316 0.385 0.554 0.643 0.439 0.141 0.009 0.008 0.010 67 0.163 0.214 0.265 0.328 0.402 0.466 0.529 0.536 0.389 0.186 0.072 0.031 0.009 68 0.163 0.201 0.232 0.294 0.397 0.476 0.522 0.506 0.365 0.192 0.103 0.062 0.031 69 0.157 0.220 0.281 0.355 0.428 0.468 0.519 0.533 0.375 0.160 0.065 0.050 0.032 70 0.153 0.198 0.248 0.304 0.354 0.431 0.590 0.664 0.449 0.143 0.010 0.005 0.008 71 0.153 0.201 0.261 0.343 0.412 0.458 0.535 0.552 0.372 0.143 0.051 0.040 0.024 72 0.151 0.207 0.259 0.316 0.391 0.466 0.517 0.487 0.353 0.210 0.114 0.042 0.006 73 0.126 0.176 0.241 0.320 0.401 0.489 0.609 0.645 0.446 0.168 0.033 0.005 0.004 74 0.161 0.203 0.237 0.270 0.333 0.456 0.608 0.618 0.406 0.179 0.081 0.038 0.010 75 0.159 0.202 0.243 0.289 0.349 0.456 0.592 0.584 0.367 0.145 0.046 0.010 0.003 76 0.076 0.148 0.260 0.351 0.375 0.411 0.515 0.518 0.321 0.134 0.082 0.053 0.008 77 0.096 0.147 0.224 0.329 0.451 0.554 0.619 0.595 0.422 0.202 0.074 0.027 0.007 78 0.160 0.216 0.272 0.318 0.372 0.434 0.455 0.411 0.344 0.276 0.169 0.060 0.018

17. Appendix C Example Combinations of Spherical Aberration

Combination C(2,0) C(4,0) C(6,0) C(8,0) C(10,0) C(12,0) C(14,0) C(16,0) C(18,0) C(20,0) No Aberr 0 0 0 0 0 0 0 0 0 0 101 0 −0.125 −0.075 0.000 0.025 −0.025 −0.025 0.025 0.000 −0.025 102 0 −0.125 −0.050 0.000 0.025 0.000 −0.025 0.025 0.000 −0.025 103 0 −0.125 −0.050 0.000 0.025 0.000 −0.025 0.025 0.025 −0.025 104 0 −0.125 −0.050 0.025 0.025 −0.025 −0.025 0.025 0.000 −0.025 105 0 −0.125 −0.050 0.050 0.025 −0.025 0.000 0.025 −0.025 −0.025 106 0 −0.125 −0.050 0.050 0.025 −0.025 0.025 0.000 0.000 0.025 107 0 −0.125 −0.025 −0.025 0.025 0.025 −0.025 0.000 0.025 0.000 108 0 −0.125 −0.025 0.000 0.000 0.025 −0.025 −0.025 0.025 0.025 109 0 −0.125 −0.025 0.000 0.000 0.025 0.000 −0.025 0.025 0.025 110 0 −0.125 −0.025 0.000 0.025 0.025 −0.025 −0.025 0.025 0.000 111 0 −0.125 −0.025 0.000 0.025 0.025 −0.025 0.000 0.025 0.000 112 0 −0.125 −0.025 0.000 0.025 0.025 −0.025 0.025 0.025 0.000 113 0 −0.125 −0.025 0.025 0.025 0.000 −0.025 0.025 0.025 −0.025 114 0 −0.125 −0.025 0.075 0.025 −0.025 0.025 0.000 0.000 0.025 115 0 −0.125 0.000 0.050 0.025 0.000 −0.025 0.025 0.025 −0.025 116 0 −0.125 0.000 0.075 0.025 −0.025 −0.025 0.025 0.000 −0.025 117 0 −0.125 0.050 0.075 0.025 0.025 0.000 0.000 0.000 −0.025 118 0 −0.125 0.075 0.075 −0.025 0.000 −0.025 −0.025 0.000 0.000 119 0 −0.100 −0.075 −0.050 0.025 0.025 −0.025 −0.025 0.025 0.025 120 0 −0.100 −0.050 −0.050 0.025 0.025 −0.025 −0.025 0.025 0.025 121 0 −0.100 −0.050 −0.025 0.025 0.025 −0.025 −0.025 0.025 0.025 122 0 −0.100 −0.025 −0.050 0.025 0.025 −0.025 −0.025 0.025 0.000 123 0 −0.100 −0.025 −0.025 0.000 0.025 −0.025 −0.025 0.025 0.025 124 0 −0.100 −0.025 −0.025 0.025 0.025 −0.025 −0.025 0.025 0.000 125 0 −0.100 0.050 0.075 −0.025 −0.025 −0.025 −0.025 −0.025 0.000 126 0 −0.100 0.075 0.075 −0.025 0.000 −0.025 −0.025 0.000 0.000 127 0 −0.100 0.075 0.075 0.000 0.000 −0.025 −0.025 −0.025 −0.025 128 0 −0.100 0.075 0.075 0.000 0.000 −0.025 −0.025 0.000 −0.025 129 0 −0.075 0.025 0.075 0.025 −0.025 −0.025 0.025 −0.025 −0.025 130 0 −0.075 0.050 0.075 −0.025 −0.025 0.000 −0.025 0.000 0.025 131 0 −0.075 0.050 0.075 −0.025 −0.025 0.025 0.000 0.025 0.025 132 0 −0.075 0.050 0.075 0.025 −0.025 −0.025 0.000 −0.025 −0.025 133 0 −0.075 0.050 0.075 0.025 0.000 −0.025 0.025 0.000 −0.025 134 0 −0.075 0.075 0.075 −0.025 −0.025 −0.025 −0.025 0.000 0.000 135 0 −0.075 0.075 0.075 −0.025 −0.025 −0.025 −0.025 0.000 0.025 136 0 −0.075 0.075 0.075 −0.025 −0.025 0.000 −0.025 0.025 0.025 137 0 −0.075 0.075 0.075 −0.025 −0.025 0.000 0.000 0.000 0.025 138 0 −0.075 0.075 0.075 −0.025 −0.025 0.025 0.000 0.000 0.025 139 0 −0.075 0.075 0.075 −0.025 −0.025 0.025 0.000 0.025 0.025 140 0 −0.050 −0.050 −0.075 0.025 0.025 −0.025 0.000 0.000 0.000 141 0 −0.050 0.050 0.075 −0.025 −0.025 0.000 −0.025 0.000 0.025 142 0 −0.050 0.050 0.075 −0.025 −0.025 0.000 −0.025 0.025 0.025 143 0 −0.050 0.050 0.075 0.025 −0.025 −0.025 0.025 −0.025 −0.025 144 0 −0.050 0.075 0.075 −0.025 −0.025 −0.025 −0.025 0.025 0.025 145 0 −0.050 0.075 0.075 −0.025 −0.025 0.025 0.000 0.000 0.025 146 0 −0.050 0.075 0.075 −0.025 −0.025 0.025 0.000 0.025 0.025 147 0 −0.025 0.075 0.075 −0.025 −0.025 0.025 0.000 0.000 0.025 148 0 −0.025 0.075 0.075 −0.025 −0.025 0.025 0.000 0.025 0.025 149 0 0.000 0.075 0.075 −0.025 −0.025 0.025 0.000 0.000 0.025 150 0 0.000 0.075 0.075 −0.025 −0.025 0.025 0.000 0.025 0.025 151 0 0.025 −0.050 −0.075 0.025 0.025 0.025 0.025 −0.025 −0.025 152 0 0.050 0.075 −0.050 −0.025 0.025 −0.025 −0.025 −0.025 −0.025 153 0 0.075 0.075 −0.050 0.000 0.025 −0.025 −0.025 −0.025 −0.025 154 0 0.100 0.050 −0.075 −0.025 0.000 −0.025 0.025 0.000 0.000 155 0 0.100 0.050 −0.075 −0.025 0.025 0.000 0.025 0.000 −0.025 156 0 0.100 0.050 −0.075 −0.025 0.025 0.025 0.025 0.025 0.000 157 0 0.100 0.050 −0.075 0.000 0.025 0.000 0.000 −0.025 −0.025 158 0 0.100 0.075 −0.075 −0.025 0.000 −0.025 0.000 0.000 0.000 159 0 0.100 0.075 −0.075 −0.025 0.025 0.000 0.025 0.025 0.000 160 0 0.100 0.075 −0.075 −0.025 0.025 0.025 0.025 0.025 0.025 161 0 0.125 0.050 −0.075 0.000 −0.025 −0.025 0.000 0.000 0.000 162 0 0.125 0.075 −0.075 −0.025 0.000 −0.025 −0.025 0.000 0.000 163 0 0.125 0.075 −0.075 −0.025 0.000 −0.025 0.000 0.000 0.000 164 0 0.125 0.075 −0.050 0.000 0.000 −0.025 0.000 −0.025 −0.025 165 0 0.125 0.075 −0.050 0.000 0.000 −0.025 0.000 −0.025 0.000 166 0 0.125 0.075 −0.050 0.000 0.000 −0.025 0.000 0.000 0.000 167 0 0.125 0.075 −0.050 0.000 0.000 −0.025 0.000 0.025 0.025

18. Appendix D Through Focus RIQ for Combinations of Spherical Aberration in Appendix C

Combination −1.50 −1.25 −1.00 −0.75 −0.50 −0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 No Aberr 0.024 0.040 0.073 0.148 0.307 0.709 1.000 0.709 0.307 0.148 0.073 0.040 0.024 101 0.071 0.102 0.206 0.371 0.466 0.446 0.409 0.397 0.365 0.305 0.236 0.171 0.114 102 0.075 0.113 0.213 0.357 0.421 0.407 0.430 0.459 0.402 0.301 0.220 0.160 0.110 103 0.071 0.106 0.224 0.382 0.431 0.388 0.385 0.405 0.374 0.309 0.238 0.173 0.120 104 0.045 0.079 0.216 0.430 0.524 0.446 0.376 0.385 0.383 0.326 0.240 0.161 0.106 105 0.043 0.075 0.203 0.427 0.551 0.478 0.377 0.355 0.350 0.314 0.242 0.160 0.101 106 0.045 0.108 0.230 0.382 0.459 0.413 0.366 0.386 0.382 0.312 0.221 0.151 0.109 107 0.032 0.091 0.212 0.323 0.360 0.391 0.463 0.483 0.407 0.317 0.255 0.198 0.141 108 0.044 0.109 0.239 0.330 0.354 0.389 0.444 0.462 0.422 0.347 0.264 0.183 0.111 109 0.029 0.106 0.231 0.314 0.358 0.427 0.489 0.478 0.403 0.321 0.251 0.176 0.107 110 0.028 0.098 0.234 0.343 0.359 0.364 0.439 0.503 0.447 0.324 0.232 0.168 0.109 111 0.033 0.093 0.221 0.343 0.385 0.402 0.469 0.514 0.446 0.326 0.234 0.168 0.113 112 0.049 0.091 0.202 0.327 0.384 0.405 0.450 0.467 0.400 0.303 0.223 0.163 0.116 113 0.048 0.082 0.211 0.400 0.476 0.408 0.365 0.391 0.387 0.325 0.239 0.167 0.118 114 0.044 0.095 0.211 0.386 0.486 0.426 0.358 0.375 0.370 0.305 0.231 0.167 0.119 115 0.053 0.096 0.212 0.360 0.420 0.374 0.361 0.416 0.420 0.340 0.239 0.164 0.119 116 0.067 0.121 0.220 0.342 0.392 0.355 0.361 0.434 0.455 0.389 0.277 0.169 0.101 117 0.039 0.095 0.206 0.321 0.369 0.365 0.383 0.422 0.418 0.358 0.268 0.180 0.120 118 0.061 0.120 0.212 0.315 0.388 0.387 0.350 0.353 0.365 0.344 0.304 0.244 0.168 119 0.065 0.127 0.213 0.309 0.364 0.393 0.432 0.436 0.395 0.342 0.269 0.183 0.111 120 0.040 0.098 0.211 0.322 0.354 0.366 0.412 0.425 0.391 0.355 0.296 0.204 0.125 121 0.039 0.104 0.236 0.352 0.374 0.383 0.441 0.469 0.426 0.351 0.264 0.173 0.102 122 0.028 0.085 0.205 0.324 0.362 0.371 0.405 0.413 0.372 0.322 0.267 0.194 0.125 123 0.039 0.083 0.201 0.313 0.367 0.431 0.486 0.458 0.392 0.348 0.288 0.192 0.105 124 0.020 0.075 0.204 0.339 0.396 0.417 0.452 0.459 0.403 0.317 0.242 0.172 0.107 125 0.044 0.096 0.203 0.327 0.395 0.383 0.359 0.389 0.423 0.393 0.304 0.194 0.101 126 0.057 0.106 0.205 0.327 0.410 0.411 0.368 0.358 0.369 0.346 0.293 0.224 0.147 127 0.038 0.087 0.200 0.338 0.402 0.383 0.367 0.388 0.397 0.359 0.282 0.194 0.123 128 0.037 0.097 0.206 0.319 0.378 0.380 0.379 0.396 0.381 0.319 0.250 0.188 0.134 129 0.053 0.097 0.219 0.353 0.404 0.378 0.365 0.397 0.395 0.323 0.235 0.163 0.112 130 0.050 0.106 0.211 0.342 0.446 0.474 0.421 0.381 0.381 0.347 0.267 0.179 0.109 131 0.058 0.121 0.201 0.302 0.420 0.465 0.419 0.397 0.393 0.330 0.238 0.161 0.104 132 0.025 0.082 0.215 0.346 0.385 0.372 0.406 0.470 0.463 0.365 0.248 0.158 0.104 133 0.059 0.103 0.205 0.318 0.370 0.369 0.394 0.451 0.437 0.328 0.219 0.151 0.109 134 0.045 0.095 0.210 0.336 0.389 0.380 0.383 0.424 0.441 0.388 0.295 0.199 0.116 135 0.046 0.094 0.209 0.331 0.379 0.374 0.371 0.392 0.413 0.383 0.303 0.207 0.121 136 0.048 0.102 0.208 0.326 0.393 0.391 0.358 0.355 0.377 0.356 0.289 0.213 0.142 137 0.028 0.082 0.201 0.325 0.378 0.368 0.367 0.418 0.461 0.422 0.319 0.200 0.103 138 0.024 0.083 0.205 0.344 0.424 0.411 0.371 0.380 0.404 0.376 0.299 0.206 0.126 139 0.036 0.107 0.214 0.316 0.387 0.398 0.373 0.388 0.408 0.363 0.278 0.191 0.120 140 0.067 0.117 0.201 0.311 0.384 0.416 0.461 0.485 0.422 0.312 0.219 0.151 0.102 141 0.055 0.105 0.215 0.361 0.464 0.483 0.431 0.379 0.364 0.333 0.256 0.169 0.101 142 0.075 0.131 0.218 0.317 0.399 0.438 0.415 0.382 0.374 0.331 0.245 0.168 0.110 143 0.052 0.090 0.204 0.350 0.411 0.382 0.371 0.406 0.398 0.313 0.222 0.161 0.118 144 0.078 0.118 0.208 0.319 0.381 0.398 0.405 0.407 0.399 0.353 0.273 0.194 0.124 145 0.028 0.086 0.212 0.359 0.437 0.421 0.381 0.386 0.403 0.368 0.286 0.192 0.116 146 0.036 0.105 0.226 0.341 0.402 0.405 0.382 0.390 0.405 0.360 0.269 0.179 0.109 147 0.035 0.092 0.218 0.372 0.454 0.434 0.387 0.383 0.391 0.352 0.272 0.183 0.111 148 0.042 0.104 0.231 0.363 0.423 0.415 0.388 0.386 0.392 0.348 0.260 0.171 0.104 149 0.046 0.102 0.223 0.381 0.471 0.449 0.391 0.374 0.371 0.329 0.255 0.177 0.110 150 0.053 0.107 0.230 0.378 0.449 0.430 0.391 0.375 0.370 0.328 0.249 0.168 0.104 151 0.087 0.139 0.218 0.318 0.389 0.428 0.447 0.425 0.379 0.315 0.228 0.150 0.103 152 0.048 0.099 0.206 0.320 0.374 0.384 0.417 0.463 0.443 0.336 0.220 0.154 0.125 153 0.042 0.095 0.205 0.324 0.375 0.387 0.427 0.466 0.430 0.318 0.209 0.153 0.130 154 0.075 0.124 0.201 0.316 0.436 0.454 0.387 0.368 0.367 0.303 0.217 0.152 0.104 155 0.072 0.118 0.205 0.348 0.488 0.481 0.376 0.359 0.381 0.320 0.222 0.157 0.118 156 0.040 0.096 0.200 0.357 0.504 0.508 0.407 0.366 0.363 0.301 0.213 0.155 0.119 157 0.047 0.097 0.202 0.355 0.455 0.420 0.357 0.393 0.426 0.345 0.223 0.156 0.132 158 0.053 0.110 0.206 0.316 0.403 0.413 0.369 0.385 0.428 0.385 0.276 0.183 0.122 159 0.071 0.127 0.209 0.315 0.415 0.418 0.355 0.370 0.417 0.368 0.260 0.175 0.126 160 0.050 0.107 0.206 0.329 0.429 0.429 0.363 0.363 0.389 0.335 0.236 0.164 0.125 161 0.056 0.121 0.211 0.304 0.386 0.420 0.400 0.393 0.387 0.319 0.226 0.161 0.121 162 0.055 0.122 0.222 0.313 0.355 0.361 0.363 0.401 0.449 0.410 0.285 0.170 0.107 163 0.063 0.129 0.233 0.335 0.403 0.411 0.363 0.354 0.400 0.387 0.291 0.189 0.118 164 0.062 0.106 0.202 0.330 0.412 0.421 0.394 0.375 0.371 0.348 0.275 0.177 0.105 165 0.050 0.107 0.217 0.345 0.423 0.426 0.379 0.351 0.361 0.332 0.240 0.151 0.101 166 0.047 0.105 0.201 0.312 0.411 0.459 0.438 0.418 0.420 0.366 0.262 0.173 0.112 167 0.053 0.119 0.210 0.307 0.405 0.466 0.447 0.416 0.394 0.311 0.212 0.161 0.122 

The invention claimed is:
 1. A lens for an eye, the lens having an optical axis and an aberration profile about its optical axis, the aberration profile: having a focal distance; and including higher order aberrations having at least one of a primary spherical aberration component (C(4,0)) and a secondary spherical aberration component (C(6,0)), wherein the aberration profile provides, for a model eye with no aberrations and an on-axis length equal to the focal distance: a retinal image quality (RIQ) with a through focus slope that degrades in a direction of eye growth; and a RIQ of at least 0.30; wherein said RIQ is Visual Strehl Ratio measured along the optical axis for at least one pupil diameter in the range 3 mm to 6 mm, over a spatial frequency range of 0 to 30 cycles/degree inclusive and at a wavelength selected from within the range 540 nm to 590 nm inclusive.
 2. The lens of claim 1, wherein the higher order aberrations include at least two spherical aberration terms selected from the group C(4,0) to C(20,0).
 3. The lens of claim 1, wherein the average slope over a horizontal field of at least −20° to +20° degrades in a direction of eye growth.
 4. The lens of claim 1, wherein the aberration profile provides a RIQ of at least 0.30 at the focal length for all pupil diameters in the range 3 mm to 6 mm.
 5. The lens of claim 1, wherein the aberration profile provides a RIQ with a through focus slope that degrades in a direction of eye growth when primary astigmatism is added to the aberration profile.
 6. The lens of claim 1, wherein the aberration profile provides a RIQ with a through focus slope that degrades in a direction of eye growth when secondary astigmatism is added to the aberration profile.
 7. The lens of claim 1, wherein said RIQ is ${{RIQ} = \frac{\begin{matrix} {\int{\int_{{- F}\;\min}^{{+ F}\;\max}{{{CSF}\left( {x,y} \right)}*}}} \\ \left( \left( \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{W\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \right) \right) \end{matrix}\ }{\begin{matrix} {\int{\int_{{- F}\;\min}^{{+ F}\;\max}{{{CSF}\left( {x,y} \right)}*}}} \\ \left( \left( \left( {{FT}\left( {{{FT}\left\{ {{A\left( {\rho,\theta} \right)}*{\exp\left\lbrack {\frac{2{\pi\mathbb{i}}}{\lambda}*{{Wdiff}\left( {\rho,\theta} \right)}} \right\rbrack}} \right\}}}^{2} \right)} \right) \right) \right) \end{matrix}}},$ wherein: Fmin is 0 cycles/degree and Fmax is 30 cycles/degree; CSF(x, y) denotes the contrast sensitivity function CSF(F)=2.6(0.0192+0.114f)e^(−(0.114f)^1.1), where f specifies the tested spatial frequency, in the range of F_(min) to F_(max); FT denotes a 2D fast Fourier transform; A(ρ,θ) denotes the pupil diameter; W(ρ,θ) denotes wavefront phase of the test case W(ρ, θ)=Σ_(i=1) ^(k)α_(i)Z_(i)(ρ, θ) measured for i=1 to 20; Wdiff(ρ, θ) denotes wavefront phase of the diffraction limited case; ρ and θ are normalised polar coordinates, where ρ represents the radial coordinate and θ represents the angular coordinate or azimuth; and λ denotes wavelength.
 8. A lens including an optical axis and an aberration profile about the optical axis that provides: a focal distance for a C(2,0) Zernike coefficient term; a peak Visual Strehl Ratio (‘first Visual Strehl Ratio’) within a through focus range, and a Visual Strehl Ratio that remains at or above a second Visual Strehl Ratio over the through focus range that includes said focal distance, wherein the Visual Strehl Ratio is measured for a model eye with no aberration and is measured along the optical axis for at least one pupil diameter in the range 3 mm to 5 mm, over a spatial frequency range of 0 to 30 cycles/degree inclusive, at a wavelength selected from within the range 540 nm to 590 nm inclusive, and wherein the first Visual Strehl Ratio is at least 0.35, the second Visual Strehl Ratio is at least 0.10 and the through focus range is at least 1.8 Diopters.
 9. The lens of claim 8, wherein the first Visual Strehl Ratio is at least 0.4, 0.5, 0.6, 0.7 or 0.8.
 10. The lens of claim 8, wherein the through focus range is at least 1.9, 2.0, 2.1, 2.25 or 2.5 Diopters.
 11. The lens of claim 8, wherein the lens has a prescription focal distance located within 0.75 Diopters (inclusive) of an end of the through focus range.
 12. The lens of claim 8, wherein the end of the through focus range is the negative power end.
 13. The lens of claim 8, wherein the end of the through focus range is the positive power end.
 14. The lens of claim 8, wherein the Visual Strehl Ratio remains at or above the second Visual Strehl Ratio over the through focus range and over a range of pupil diameters of at least 2 mm.
 15. The lens of claim 8, wherein the higher order aberrations include at least two spherical aberration terms selected from the group C(4,0) to C(20,0).
 16. The lens of claim 8, wherein the higher order aberrations include at least three spherical aberration terms selected from the group C(4,0) to C(20,0).
 17. A method for a presbyopic eye, the method comprising forming an aberration for the eye and applying or prescribing the aberration profile, the aberration profile: having a focal distance; and including at least one of a primary spherical aberration component (C(4,0)) and a secondary spherical aberration component (C(6,0)), wherein the aberration profile provides, for the eye: a retinal image quality (RIQ) with a through focus slope that degrades in a direction of eye growth; and a RIQ of at least 0.30; wherein said RIQ is Visual Strehl Ratio measured along the optical axis for at least one pupil diameter in the range 3 mm to 6 mm, over a spatial frequency range of 0 to 30 cycles/degree inclusive and at a wavelength selected from within the range 540 nm to 590 nm inclusive.
 18. The method of claim 17, wherein applying or prescribing the aberration profile comprises providing a lens, the lens having an aberration profile including at least two spherical aberration terms selected from the group C(4,0) to C(20,0).
 19. The method of claim 17, wherein the method further comprising identifying a wavefront aberration profile for the hyperopic eye and applying or prescribing the aberration profile, the wavefront aberration profile including at least one spherical aberration term, wherein the prescription focal distance of the lens is determined taking into account said spherical aberration and wherein at the prescription focal distance the wavefront aberration profile provides an improving retinal image quality in the direction posterior to the retina.
 20. The method of claim 17, the method further comprising identifying a wavefront aberration profile for the presbyopic eye, the wavefront aberration profile including at least one spherical aberration term, wherein the prescription focal distance of the lens is determined taking into account said spherical aberration and wherein the prescription focal distance of the lens is at least +0.25 D relative to a focal distance for a C(2,0) Zernike coefficient term of the wavefront aberration and producing a device, lens or corneal profile for the eye to affect said wavefront aberration profile. 